CA2349809C - Kidney dialysis - Google Patents

Abstract

Methods are disclosed for providing operationial instructions to a hemodialysis circuit (10) having a dialysis filter (48) and a capability of operating according to a time-varying parameter such as variable ultrafiltration. According to the methods, entered are a desired time period, a target cumulative value of the parameter, such as target ultrafiltration volume, and a proposed time-varying profile of the parameter that is representable as a plot of coordinates in a region defined by an ordinate of values of the parameter and a time-based abscissa defining a profile cumulative value of the parameter. If the profile cumulative value is not equal to the target cumulative value, then the proposed time-varying profile is changed along the ordinate to make the cumulative values equal. The circuit (10) then operates according to the changed profile to achieve the entered target cumulative value within the time period.

Description

, . 78749-3D
- la -This is a division of our co-pending Canadian Patent Application 2,149,246 of 12 Nov. 1993.
The present invention relates to improvements in kidney dialysis machines and to a method of providing operational instructions to a hemodialysis machine.
BACKGROUND OF THE INVENTION
Kidney dialysis machines are well known in the art and are illustrated, for example, in U.S. Patents 3,598,727, 4,172,033, 4,267,040 and 4,769,134.
While machines according to the prior art provide a number of advantageous features, they nonetheless have certain limitations. The present invention seeks to overcome certain drawbacks of the prior art and to provide new features not heretofore available.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a method of providing operational instructions to a hemodialysis system, so as to enable the system to operate according to an operational parameter that can vary over time, the method comprising: (a) providing a user/machine interface that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system; (b) enabling an operational parameter to be selected; (c) enabling a time period to be entered into the system; (d) enabling a target cumulative value corresponding to the operation parameter to be achieved while operating the system during the time period to be entered into the system; (e) enabling a time-varying set of data corresponding to the operational parameter to be executed by the system during the time period to be selected, the set of - lb -data being representable as a plot of coordinates in a region defined by an ordinate of values of the parameter and a time-based abscissa, the plot defining a proposed cumulative value of the parameter; and (f) adjusting the time-varying data to make the proposed cumulative value equal to the target cumulative value, so as to allow the hemodialysis system to achieve, while operating, the entered target cumulative value within the time period.
According to another aspect of the present invention, there is provided a method of providing operational instructions to a hemodialysis system having ultrafiltration capability, so as to enable the system to perform ultrafiltration of fluid from a patient according to a time-variable set of ultrafiltration data, the method comprising:
(a) providing a user/machine interface that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system; (b) enabling an indicium corresponding to ultrafiltration to be selected; (c) enabling a prescribed time for dialysis to be entered into the system; (d) enabling a target ultrafiltration volume of fluid to be removed from the patient to be entered into the system; (e) enabling a proposed time-variable set of ultrafiltration data being representable as a plot of coordinates on an ultrafiltration rate axis and a time axis and defining a proposed ultrafiltration volume to be selected; and (f) adjusting the proposed time-variable set of ultrafiltration data to make the proposed ultrafiltration volume equal to the target ultrafiltration volume, so as to allow the hemodialysis system to achieve, while ultrafiltering the fluid according to the adjusted ultrafiltration data, the entered target ultrafiltration volume within the entered prescribed time.
According to still another aspect of the present invention, there is provided a system for performing . . 78749-3D
- lc -hemodialysis comprising: (a) a dialysate-delivery system for supplying dialysate to a hemodialyzer; (b) a blood circulation system for delivering blood from a patient through a blood compartment of a hemodialyzer, and back to the patient; (c) a user/machine interface operably connected to the dialysate delivery system, the user/machine interface displaying information relating to a hemodialysis treatment and allowing a user to control functions of the hemodialysis system, said user/machine interface being operable to allow a user to select a prescribed time for dialysis, a target ultrafiltration volume, and a proposed time-variable set of ultrafiltration data; and (d) a processor which adjusts the ultrafiltration data selected by the user to allow the hemodialysis system to achieve, while ultrafiltering the fluid according to the selected ultrafiltration data, the entered target ultrafiltration volume within the entered prescribed time.
The present invention provides a method of providing operational instructions to a hemodialysis system, so as to enable the system to operate according to an operational parameter that can vary over time, the method comprising: (a) providing a user/machine interface including a touch screen that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system by pressing portions of the touch screen; (b) selecting an operational parameter using the touch screen; (c) entering a time period; (d) entering a target cumulative value corresponding to the operational parameter to be achieved while operating the system during the time period; (e) selecting a time-varying profile of the operational parameter to be executed by the system during the time period, the profile being representable as a plot of coordinates in a region defined by an ordinate of values of the parameter and a time-based abscissa, the plot defining a profile cumulative value of ' ~ 78749-3D
- ld -the parameter; and (f) adjusting the time-varying profile to make the profile cumulative value equal to the target cumulative value, so as to allow the hemodialysis system to achieve, while operating, the entered target cumulative value within the time period.
The invention also provides a method of providing operational instructions to a hemodialysis system having ultrafiltration capability, so as to enable the system to perform ultrafiltration of fluid from a patient according to a time-variable ultrafiltration profile, the method comprising:
(a) providing a user/machine interface including a touch screen that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system by pressing portions of the touch screen; (b) selecting an indicium on the touch screen corresponding to ultrafiltration; (c) entering a prescribed time for dialysis;
(d) entering a target ultrafiltration volume of fluid to be remove from the patient; (e) selecting a proposed ultrafiltration profile being representable as a plot of coordinates on an ultrafiltration rate axis and a time axis and defining a profile ultrafiltration volume; and (f) adjusting the proposed ultrfiltration profile to make the profile ultrafiltration volume equal to the target ultrafiltration volume, so as to allow the hemodialysis system to achieve, while ultrafiltering the fluid according to the adjusted ultrafiltration profile, the entered target ultrafiltration volume within the entered prescribed time.
The invention further provides a system for performing hemodialysis comprising: (a) a dialysate-delivery system for supplying dialysate to a hemodialyzer; (b) a blood circulation system for delivering blood from a patient through a blood compartment of a hemodialyzer, and back to the patient;
(c) a user/machine interface operably connected to the > 78749-3D
- le -dialysate delivery system, the user/machine interface comprising a touch screen that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system by pressing portions of the touch screen, said user/machine interface being operable to allow a user to select a prescribed time for dialysis, a target ultrafiltration volume, and a proposed ultrafiltration profile;
(d) a processor which adjusts the ultrafiltration profile selected by the user to allow the hemodialysis system to achieve, while ultrafiltrating the fluid according to the selected ultrafiltration profile, the entered target ultrafiltration volume within the entered prescribed time.
The invention will further be described, by way of example only, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. lA and 1B comprise a schematic hydraulic diagram of a preferred embodiment of a kidney dialysis machine according to the present invention.
FIG. 2 is a schematic diagram showing flow path locations and components of a pre-dialyzer flow sensor and a post-dialyzer flow sensor according to the present invention.
FIGS. 3A and 3B are isometric and schematic diagrams, respectively, of a concentrate-line proximity sensor comprising a portion of the automatic proportioning mode setting feature of the present invention.
FIG. 4 is a schematic diagram showing the interconnection of input and output pressure equalizers into the hydraulic flow path of the present invention.
FIG. 5 is a schematic diagram of the automated drip-chamber level adjusters of the present invention.

' 78749-3D
- 1f -FIG. 6 is a schematic diagram of a preferred embodiment of a means for increasing dialysate flow velocity through the dialyzer without increasing the dialysate flow rate.
FIG. 7 shows a block diagram of a computer system used in the preferred embodiment.
FIG. 8 shows a touch screen display used in the preferred embodiment.
FIG. 9 shows the touch screen of FIG. 8 with a calculator window for data entry.
FIG. 10 shows a profile entry screen used in the preferred embodiment.
FIG. 11 shows a programming screen used in the preferred embodiment.
DETAILED DESCRIPTION
Hydraulic Circuit A hydraulic circuit 10 representing a preferred embodiment of an improved hemodialysis machine according to the present invention is illustrated in FIGS. lA and 1B. The hydraulic circuit 10 is comprised of the following principal components: an incoming water pressure regulator 12, a water on/off valve 14, a heat exchanger 16, a heater 18, a safety WO 94~ . . 93 PCT/US93/10991 thermostzt 20, as "-A"concentrate pump 22, a supply valve 24, an air gap chamber 26. as 'A' rinse fitting 28, a "B'rinse fitting 30, a deaesstion sprayer 32, an air removal pump 34, a vented air trap 36, as 'A"conductivity probe 38, a "B' conceattate puatp 40, a supply pump 42, a 'B" miu chamber 44, a "B"conductivity probe 46, a dialysate filter 48, a supply regulator S0, an input prGSSUre equalizer 52, a flow equalizer 54, as output pt~tue equalizer 56, ead-of stroke seasons 59, a dialysate condssctivity probe 60, a pre-dialyzer flow sensor 62, a dialysate prn~tre t:aasducer 64, a bypass valve 66. a dialysate sample port 68, a post~ialyzer flow aeasor 70. a dialysate p:csnue pump 72. a OF removal regulata~r 74, a OF flow meter 76, s blood-kak daector 78. and a rinse valve 80. The :foeemeatiaoed compoaeats are iatezsonaected as shown in FIGS. lA and 1B.
T~ iacomiag water pressure regulator 12 is coupled to a presstuized water source 82 and redisca and stabilizes the water supply psesnsre to a level of about 20 psig.
The water on/off valve 14 opens whey machine power is on. thereby allowing , water to flow from the source 82 into the hydraulic circuit 10. When the machine power is off, ' the water onloff valve 14 is closed.
The heat exchanger l6 transfers heat from "sport" or effluent dialysate.
passing through conduit 84. to the cooler incoming water psasiag through conduit 86 as these two liquids pass cosmtercurreatly through sepuate but adjacent comptrlmGnts in the heat e~tmger 1G. Ia this way. the isscosniag water is warmed, which reduces the amount of heat energy that must be supplied to the water by the beta 18.
The heater 18 further warms the iaooming water to s suitable tempes'ature for hemodialysis. which is shout 38 °C. A typical heater 18 is a resistance type known in the art, rated at about 1500 watts. The hater 18 includes a dowa~am thermistor 20 or analogous temperature-se»siag device. A thermistor as known is the art is esseatislly a tempersatre-sensitive reaisior which eaperieaxs a change in electrical resistance that is inversely proportional to a corrsspoadiag change in temperadsre. The thermistor 20 is couplod to the mrchine's a>icrnpcocessor (not shown is FIGS. lA and 1B) which utilizes signals from the tbamistor for turning the hater 18 on and off as required to maintain the water temperature at the proper level.
The 'A'coaceatrate pump 22 propels either "acid'or "acetate" coaceatrate as Icaovtm in the art from s container thereof 88 into the air gap chamber 26.
The 'A' coac:tntrate pump 22 is a feed-voluate cam-drivers pump. A super nwtor 90 calibratsble to route a precise number of rotations per minute is preferably used to drive the 'A'conxatrate pump 22. The stepper motor includes a shaft (not shown) to which is mounted a cam (not shower) which eagsges a fleuible diaphragm 92, thereby delivering a known volume of 'A' concentrate per each rotation of the cam. An optical sensor (not shown) on the cam monitors the angular rotation of the cam for ptvcessing by the microprocessor (not shown). The microprocessor, using information pertaining to dialysate flow rate and coaceatrate parameters _ . _ _ J PCT/US93/10991 :a -3- ' entered by the machine operator using a touch screen (described is detail hereinbelow), calculates the amount of concentrate nxessary to achieve a correct ratio of water and "A"
conxatrate for hcmodialysis therapy. The microprocessor thereby adjusts the angular velocity of the stepper motor shaft.
An "A"concentrate line 94 is used to deliver "A"concentrate from the supply 88 thereof to the "A"concentrate pump 22. When rinsing the machine. the 'A"conc~strate line 94 i: coupled to the "A"rinx fitting 28 which serves as a source of rinse warn for the "A"
true line.
Whey disiafeexiag the machine, the 'A"coacaitsae line 94 is coupled to a disinfect fitting 96 which enables the 'A'trata pump 22 to deliver a chemical disWafecsant to the 'A'co~atrate line 94. ~ .
Heated water eaters the air gap chamber 26 through the supply valve 24. The supply valve 24 is actuated by a lever 98. The lever 98 is coupled to s float 100 inside the air trap 35. Thus. the float 100 controls water flow into the hydraulic cirmit 10 by opening the supply valve 24 when the water Level supporting the float drops and by cloning the supply valve 24 when the water level in the air trap 36 rises.
The air gap 102 is the chamber 26 is at aomospheric pry. '~ air gap 102 l~ Prevent incoming wiser from flowing backwssrl (ups~m) in the event of a presaare drop in the water supply 82.
A P~~~ty sensor (not shown is FIGS. IA and 1B but described is further detsil hereinbelow)~ is built into the "A"rinse fitting 28. The proximity sensor senses whey the "A"concentrate line 94 is coupled to the "A"rinse fitting 28 and whey it is not, thereby serving as as important safety interlock feature which prevents unsafe operation of the machine.
The "B"rinse fitting 30 supplies water for rinsing the "B"concentrate line 104.
~8 rte. the "B"conaatrue line 104 is coupled to the "B"rinse fitting 30.
During acetate dialysis. the "B"concentrate line 104 is also coupled to the "B"rinse fitting 30 for rocirculatioa of acwte dialysate solution therethrongh.
The "B"rinse fitting 30 is also provided with a proumity sensor (not shown in FIGS. IA and 1B but described is further detail herzinbelow) similar to thst providod with the 30 "A'riase fitting 28.
The hydraulic circuit includes coatpoaeats operable to remove dissolved gases from the liquid passing therethrough. Otherwise, if the liquid were not deaerated, dissolved gases therein could adversely affect the course of a'dialysis treatment.
including the accuracy at which the machine performs ultrafiltration of the patient. To facilitate deaeration, liquid flows 35 through the air-removal sprayer 32 at a rate of about 1500 mLmin at a subatmospheric pressure (about 500 mmlig). The reduced pressure is attaiaod by aspirating the liquid via the air-removal pump 34 through a flow restrictor 106 upstrram of the air-removal sprayer 32.

-The air-removal sprayer 32 breaks the liquid into small droplets as it is subjxted to the substmospheric pressure, which favors the formation of air bubbles.
The air trap 36 vents air bubbles libe:sted from the liquid by the deaerstion sprayer 32 through a vent opening 108 open to the attnosphere. The sir trap also contains the float 100 discussed hereinabove. , The 'A"coaduaivity probe 38 measures the electrical conductivity of the mixture of water and 'A"concentrate. Conductivity is an acatrate way to a~scettain whether the 'A' canceatrate solution has been correctly proportioned. The conductivity meastrr~ed at the 'A' conductivity probe 38 can vary depending upon the ionic strength and electrolytic profile of the 'A'coaceatrate. Since conductivity will be affected by temperature, the 'A'condttctivity probe 38 is also provided with a thermistor 110. The thermistor 110 is coupled to the microprocessor (not shown) which performs the necGSSary temperaatre compmsstioa.
The 'B"concentrate pump 40 delivers bicarbonate concentrate from a supply thereof 112 and is operable only during bicarbonate dialysis therapy. The 'B'concentrate pump 40 is a fixed-volume cam~riven pump similar to the 'A"concentrate pump 22. The "B' conceattate pump 40 is drives by a stepper motor 114. As with the 'A'conceatrate pump, the angular velocity of the stepper motor shaft is monitored by as optical sensor.
The optical sensor is connected to the machine's microprocGSSOr which calculates the amount of 'B".
cooaatrate neoe~ary to achieve a correct dialysate composition for safe hemodislysis therapy sad correspondingly controls the angular velocity of the cam. The "B"concentrate pomp 40 will automatically com~sate for changes in dialysate flow rate in the event that said flow rate is changed during a dialysis treatment by increasing or decreasing the pump rate.
FIGS. IA sad 1B also shows an optional third concentrate supply 116, a third fixed-volume cam-driven concentrate pomp 118 operable in the same manner as the "A"sad 'B"concentrate pumps 22. 40. a corresponding mixing chamber 120 and conductivity probe 122.
The "B'mix chamber 44 provides thorough taixing of the 'B"coaceutrste with the proportioned mixture of 'A'conceatrate and water to form dialysate before the dialysata crates the 'B'conductivity probe 46.
The 'B' ~nducrivity probe 46 monitors dialysate conductivity. Electronic .circuitry (not shown) coupled to the 'B'condttctivity probe 46 subtracts the conductivity mea~tr~ed at the 'A"conductivity probe 38 from the conductivity measured at the 'B' oooductivity probe 46. During acetate dialysis. the difference in these conductivity readings s~bould be zero. Since conductivity mxutremeau are affected by temperature, a thermistor 124 is included with the 'B'coaductivity probe 46 to ptrnride temperature compensation of the 'B"conductivity reading. The thermistor 124 also comprises a portion of a redundant high temQeracure alarm subsystem.
Before describing the hydraulic circuit any further, it is appropriate to briefly describe the flow equalizer 54. The flow equalizer 54 comprises a first chamber 126 and a _ _ _. ..~...., .,.m .
_j-second chamber 128 of substantially equal volume. Each chamber 126, 128 is comprised of ~'o ~mpartmeats. one termed a "pre~ialyzer" or "pre" compartment 130. 132 and the other a "post-dialyzer"or "post~compartmeat 134, I36. Each pair of opposing "pre~aad -post-is dated by a flexible diaphragm 138, 140. Solenoid-actuated valves 142-149 control the filliagaad emptying of each compartment. In general, each compzrtmeat l30. 132.
134, 136 is completely filled befort its contents are discharged. Also. the "pre" compartmeata 130,132 are alternately filled and discharged and the -post- compartments 134,136 are alternately filled and discharged. Also. filling a -pre' compartment 130,132 noses a °°~Po~~B charge of as opposing "post- ~mpa~~t 134,136.
~pe~ively. The "pre' compartments 130,132 alternately fill from the supply pump 42 and altecaatdy did to the dialyzer. The -post' compartments . 134, 136 alternately fill with "spent"
dialysate retarnm8 ~
the dialyztt and discharge the span dialysate to a drain line 150. For example, dialysate from the supply Pump 42 eaters the -pre" compartment 132. thereby displacing the diaphragm 140 is FIGS. IA and IB to the right, causing the ~post'~~~t 136 to empty.
Simultaneously, 'post-compartment, 134 fills while -pre" compartment 130 easpties.
The flow equalizer 54 operates via a four-phase cycle. In the fiat phase, valves 142.145,147, and 148 tern on. thereby filling the 'pr,e~ comp~t 130 with fresh dialyaate ~ ~P~B ~ dsa~tragm 138 to the right is FIGS. lA and 1B. Such disptacea~at of the ~phra8m 138 expels 'spent' dialysata containal in the "post' compartment 134, which has a volume equal to the volume is the -pre' compast~t I 30, to pass to the ~ drain line 150. At the same time, effluent dialysate from the dialyzes eaters the -post"
compartment 136, thereby forang the diaphragm 140 to be displaced to the left in FIGS. IA and IB to expel an equal volume of fresh dialysate from the "pre" cost 132 to the dialyzes. In the second phase.
all the solenoid valves I42-I49 turn off for a short period of time (about 125 cosec). 'This brief shut-off' eliminates adverse affects on ultrafiltration accuracy that would otherwise result if at least two of said valves were open at the same time. Ia the third phase, solenoid valves 143, 144, l46, and 149 are energized, caus~g the ~p~t~ ~~t~t 134 to fill with effluent dialysate from the dialyzes. thereby expelling fresh dialysate from "pre-compartment 130 to the dialyzes. Also. the 'pre' compartment 132 simultaneously fills with frtsh dialysste from the supply Pump 42. ~rtby expelling effluent diaJysate from the rtaraining -post"oompart~t 136 to the drain Line I50. Ia the fourth phase, all the solenoid valves 142-149 are again turned off for about 125 cosec.
Since the volumes of opposing "pre' and -post- compart~ts 130, 134 and 132, I36 are equal, the flow equalizer 54 volumetrically balances the flow of dinlysate to and from the dialyzes. A further benefit of such volumetric equality is that dialysate flow to the dialyzcr can be accurately measured over a wide range of flow rtes.
The supply Pump 42 has two functions: (a) to supply as adeQuate dialysate flow volume and pressure to fill the flow equalizer compartments with dialysate, and (b) to create a flow of dialysate through a loop 152 comprised of the dialysate filter 48, the supply regulator S0, the 'B"mix chamber 44, and the 'B'conductivity probe 46. The supply pump 42 delivers dialysate at a maximum regulated pressure of 12.5 psig and at a flow rate approximately 50 mLlmin higher than the dialysate flow rate set by the ope:ator using the touch screen.
The dialysate filter 48 is used to occlude downstream passage of particulate . . forage material into the flow equalizer 54. The supply regulator 50 is adjusted to an output prawtre of approximately 16 prig. Whenever the 'pre' and 'post" compartments of the flow equalizer 54 reach the end of a fill cycle during phases 1 or 3, pressstre builds up is the loop 152. As the pres~e increases to about 16 prig, the supply regulator 50 opens sufficiently to pass the dialysate output of the supply pump 42 through the loop 152 until the tuzt phase 1 or 3.
Tha input pressure equalizer ~52 equilibrates hydraulic pc~essitres at the idets 155 of the flow equalizer 54 so that the compartments 130,132.134,136 fill at the same rate.
Likewise, the output prartu~e equalizer 56 equilibrates hydraulic prrssures at the outlets 156 of the flow equalizer 54. The input and output pres~u~e equalizers are discussed is grass detail 6aexabelow.
The input pure equalizer 52 also automatically equilibrates the pressure of the dialysate flowing through the downstream lines 158.160 with the pressure of dialysate at the flow equalizer inlets 154. Whmeve: the pt~atre at the flow equalizer inlets 154 exceeds the p~ue geaented . by the dialysate pressure pomp 72. the input prcssttre equalizer 52 t~tricrs the flow of dialysate is lines 158,160. Such equilibration of pressures allows both chambers 126. 128 in the flow equalizer 54 to be filled st identical rates.
End-of-stroke sensors 162. 164 are provided at the outlets 156 of the output pressure equalizer. The ead~f-stroke sensors 162.164 verify whey the flow equalizer compartments have reached the end of a fill cycle (end of stroke). When the compartments are full, the end-of-stroke sensors 162.164 send a no-flow signal to the machine's microprocessor. indicating that the compartments are full.
'Ibe dislysate conductivity probe 60 meastues the conductivity of the dialysate before it eaters the dialyzcr. The machine's micrvproc~.essor compares the measured caoductivity with as expoctod conductivity value (discussed in detail heniabelow) based upon oooceatrate formulation information entered by the operstor using the touch screen. If the measured dialysate conductivity is excessively above or below the expected conductivity value.
the machine's microprocessor activates a conductivity alarm. Also, the bypass valve 66 is tsiggered dutsng a cmtductivity alarm to divert dialysate away from the dialyra through conduit 166.
.tee dialysate conductivity probe 60 includes a thermistor 168 which allows temperature compensation of the conductivity reading. The electronic signal from the thermistor 168 is also utiiized to provide a dialysate temperature display oa the machine's y..~ .rJJJI ~V//
.7.
touch scrten as well as primary high and low temperature alarm limits. The dialysate conductivity as measured by the conductivity probe 60 is also displayed on the machine's touch sct~eea.
The dialysate flow sensor 62 includes a self-heating variable thermistor as ,yell as a refetrace thermistor (not shown in FIGS. I A sad 1 B. but discussed in detail dory,).
The dialysate flow sensor 62 is used mainly as a bypass monitor. Whenever the machine is is bypass, the rrsulting lack of dialysate flow past the flow sensor 62 serves as a verification that .
the bypass valve 66 is fin~ioning cori~ly, .
The dialysate pre~ra ~ucer 64 xases dialysate pr~,a sad converts the prautne reading into an analog signal prnportianal to the dialysate pr~re. The analog signal is utilized by the machine's microprocessor as the, basis for a dialysate presam,e display on the touch sc:eea, pressure alarms. sad other dialysate control functions (not shown is FIGS. IA sad 1H).
The bypass valve 66 protects the >umodialysis patient ° the event of a tt~emture or c~adyctivity alarm by divesting dialysate flow away from the dialyzer. 'Ibe bypass valve 66 is a three-way solenoid valve which. whoa triggered, occludes the conduit 170 leading to the dialyzer sad shoats the dia(ysate flow through conduit 166 to a location 172 doavnatrrara of the dialyzer.
~ ~1Y~ sample port 68 is as appliance which allows the operuor to obtain a die of the dialysate using a syringe for indt Wig, A second dialysate flow xasor 70 is located in the post-dialyzer ("venous ") line 174. The second flow sensor 70 is constntcted similarly to the first flow sensor 62 sad is discussed is detail herranbelow. The second flow sensor 70 is utilized for checking the axuracy of the machine's ultrafiltration capability.
The dialysate pressure pump 72 is situated downstream of the dialyzer. Aa ~°°~Y~B ~mulatioa loop comprising lines 158. 160 conducts effluent dialysate to the idet Ptaxure equalizer 52. The recirculation loop 158, I60 thereby helps equilibrate pr~tu~e diffeszaces that might otherwix be transmitted to the flow equalizer 54 sad also serves as a source of hydraulic prGSSUre sufficient to fill the OF flow meter 76 whoa demanded thereby.
~ The dialysate pr,exune pump 72 circulsta dialysste st a constant flow rate of 1~0 mLmin through the recirzulation loop 158,160 without affecting the overall dialysate flow rate through the hydraulic circuit 10. As a result, the dialysate pr~ux pump 72 is usable to adjust pressure differences across the dialyzer membrane.
As long as the dialysate pressure pump 72 roceives as adoquate volume of 35 dialysate for pumping, the flow dynamics of dialysate through the hydraulic circuit IO are unaffected. However, should liquid be neraoved from the rrcirculatioa loop 158, 160, the dialysate pressure pump will attempt to replact that lost volume by demanding more volume from the dialyrcr. Since the flow equalizer 54 maintains volumetric constancy of dialysate _g_ passing to and from the dialyzer, the only fluid available to replace any fluid lost from the loop 158, 160 must come from the dialyzer itself. Hence, by precisely controlling the amount of liquid removal from the rxirculation loop 158, 160 (using the OF flow meter 76), the operator can precisely control the amount of liquid that must be nemovod from the hemodialysis patient via the dialyzer.
Since the dialysste pumped by the dialysate pz~wtre . Pump 72 has a partially t~ticted flow, a sufftcieat pry is thereby provided at the input of the OF
removal ..
rogdator 74. 'The OF removal rogulator 74 regulates hydraulic pnesatro at the iapttt 178 of the OF flow meter 76.
The OF flow meter 76 is coa>prised of a chamber 180 separated into two sttbcomparaaeats 182,184 via a disphragm 186. Each subcompartmeat 182,184 has a corresponding valve 188,190. rapoaively, associated therewith. Either subcompartmdu 182, .
184 of the OF flow teeter 76 can only fill when the cotr~diag valve 188, 190 is opened.
Whenever a first subcompartmeat 182 is filling. the opponiag sec~ad compartraeat 184 is emptying its conceals to a drain line 192. The rate of OF removal through the OF flow meter ?6 is governed by the rate at which the ootr~poodiag valves 188,190 are alternately opened sad cloned.
VVluaever liquid leaves the rxirctttation loop 158,160 through the OF flow miser 76, oor:~oadiagly less liquid is recirculatod through the recirculation loop 158,160. This caaxs a corresponding "starntion' at the input 172 of the dialysate pressure pump 72 which a ~rraspondiag doc~e in dialysste pt~rre is the dialyzer. The dectrased dialyaste pressuro causGS a volume of liquid to be removed from the pstieat that is equal to the volume of liquid removed from the rxirculatioa loop 158, 160 via the OF flow meter 76.
These volumes will be equal so long as the dialyzer has an ultrafiltration capability sufficient to remove said volume from the patient a the desired rate.
Efllueat dialysate ezpellod from the flow equalizer 54 passes through and is moaitoned for the presence of blood by the blood-leak detector 78. The blood-leak detector 78. discussed is further detail hereinbelow, comp:ises a light source 194 and a photocell 196 which monitors light.traastnitted through the effluent dialysate solution passing thetsth:ough.
If blood leaks through the dialyner membrane from the pstieat into the dialysate. the dialysate P~8 Hugh the blood-leak detector 78 will absorb a portion of the light passing tharethrnugh. The corresponding docttsu in the amount of light reaching the photocell 196, if the daxease is excessive, triggers a blood-leak alarm by the machine.
Efllueat dialysste from the blood-leak detector 78 is routed through conduit 84 to the heat eachaager 16, then to a drain 198.
The rinse valve 80 allows the OF flow meter 76 to remove rinse water fmm the recirculatioa loop 158, 160 at a rate of about 4 LJh. Such rinsing ensures as adoquate flushing of the recirculatioa loop 158. 160 and OF flow teeter 76. However, since liquid is removod from the loop 158,160 at a relatively high rate during rinse, the rinse valve 80 also allows an equivalent volume of liquid to be added back to the loop 158,160.
User Interface In the preferred embodiment, a touch screen user interface is employed.
Touch screens are known in the art and are commercially available from a number of sources, including Elographics West of San Diego, Cal. The use of touch screens in user interface applications for medical equipment is also known, as shown for example in US Patents 4,974,599 and 4,898,578.
In the prior art, as illustrated by the above-referenced patents, touch screens have been used in conjunction with computers and CRTs to provide a control panel that can be changed under computer control. The means by which a computer, a CRT, and a touch screen can be cooperatively operated in this fashion is well known and does not, per se, form a part of this invention.
FIG. 7 shows a block diagram of the computer system 500 that is used to control the touch screen 501, CRT display 503, and other components of the apparatus. This computer is programmed in the language 'C' in a conventional manner to accomplish the dialogue and other functions subsequently described.
FIG. 8 shows the touch screen display that is usually presented to the operator of the system of FIG. 7. As can be seen, the primary treatment parameters are displayed. These include the heparin pump rate, the dialysate flow rate, the dialysate conductivity, the dialysate temperature, the elapsed 9a treatment time, the total ultrafiltrate removed, the transmembrane pressure, and the ultrafiltration rate. Also displayed are the patient's arterial and venous blood pressure (both in column of mercury form and in numeric form). A linear indicator at the bottom of the screen indicates the blood pump flow rate. A space at the top of the screen is reserved for alarm and help messages.
Most of these display elements are in a bordered box.
The border serves as a visual alarm indicator and changes color and flashes if a corresponding alarm limit is violated.
A number of buttons are displayed on the right hand side of the display. The first is a RSET button and is used to reset alarm conditions after an alarm condition is corrected.
HELP guides the user through a variety of help messages. SET
LIMITS sets the alarm limits for various parameters including arterial pressure, venous pressure and TMP. MENUS replaces the buttons on the right hand side of the display with additional buttons corresponding to additional control functions, while maintaining the displayed parameters elsewhere on the screen.
RINSE initiates the rinse mode, provided the interlocks are met. MUTE silences most audio alarms for 100 seconds.
Additional buttons can appear in this part of the screen.
Button locations are reprogrammable and can have multiple legends associated with them. Also, their positions on the touch screen can be varied by reprogramming.

i If it is desired to change one of the displayed parameters, such as the heparin pump rate, the operator simply touches the corresponding indicator. A
calculator-like keyboard then pops up in a window superimposed on the display, as shown in FIG. 9. On this keyboard, the user can eater the new value for the selected parameter. Once the desired parameter is catered in this fashion, the operator presses ENTER on the calculator display _ and the calculator display disappars. The revised parameter is substituted is the , cocz~potsding indicator (with its border highlighted) and the user is prompted, through a .
button that appears at the Iowa right hand side of the scrxn. to verify the eatand change. If the YERIFY button is not totached shortly after displayed. the VERIFY button di~pparr and the machine continues with its previous paraaoeter. If timely verified, the change takes effect.
In the preferred embodiment, the user has baween one and five seconds to verify the Soma parameters are not susceptible to repres~tstion by a single number dispLyed in a parameter window. E:emplary are parameters that ara programmed to change over time (so~allod profiled parameters). In this class are the sodium concentration of the dialytaite solution. the bicarbonate coaoentratioa of the dialysate solution.
kT/V, and the ulttafiltratioa rate.
1a the pnferrnd embodiment. such profiled parameters are selectably displayed in the form of bar grsphs on the display scsxa. Using sodium as as exampi0. the Y-nuts rats sodium cotxxatrations is the range of 130 - 160 mEqlL. Tha X-axis its the treatment period. broken down into fifteen minute intervals. Such a display is shown in FIG.
10.
The use of bar graphs to display profiled parameters is known in the art. The prior srt fails. however, to provide a convenient manner by which data characterizing the profile curve may be catered into the machine. Typicxily, such data entry has bees axomplished through a keypad on which data for each discrete time period is catered.
However. this approach cequira domas of key presses and provides numerous opportunities for error.
In the preferred embodiment, in contrast, profiled parameters aro catered by simply tracing the desired profile curve on the touch screen.
Ia more detail. programming of Profiled parameters is performed as follows:
From the main touch screen display of FIG. 8, the user press MENUS. The ProBm~g ~reea of FIG. 11 rhea appears, which includes along its right hand side buttons corresponding to the programming of sodium, biarboaste, kTIV, sad ultrafiltrstion. The parameter desired to be programmed is rhea selected by touching the corresponding button.
Ia response to this touch, the scrxa of FIG. 10 appears. If a profile has already bees programmed, it is displayed in bar graph fashion on this screen.
Otherwise, the graph is empty.

Before permitting the user to program the sodium profile, the machine first solicits the sodium value of the sodium concentrate being used. This data is catered on a pop-up keypad. If the treatment time was not earlier programmai, the machine also solicits this data by means of a pop-up keypad.
The user then traces the desired profile curve on the touch screen. and the cotaputa virtually simultaneously displays s series of bars corresponding to the traced curve.
Alternuively, the user can touch the scrxa at discrete points ar the desired profile carve. To program a linear iacrnse in sodium from 140 to 160 the user would touch the graph at 140 at the ordinate co ~' for a~um~e, ~~g to the beginning of the trca~ent interval. and 160 at the ordinate cog ~ the cad of the trot interval.
The computer would then fit s linearly inctt~irtg series of bars betvveea these points.
Discrete touches can also be used to program stepped Profiles. If the first hour of trsstmeat is to be at I50 mF.q/L sad the second bow is to be at 135 mEqlL, the user would first touch the scrxa at 150 at the ordinate cott,~pondiag to the beginning of the first hour. At the ordinate corr~poadiag to the cad of the first hour. the user would puss at two locations. First at 150 (to cause the computes to fill is the intervening period with bars ootre,~poading to 150), sad again at 135. Finally. the user would touch the screen at 135 at the oo~spoodiag to the cad of the second hour. The computer would rhea 611 is the second hour with bars corresponding to 135.
After the desired profile curve has bees eater,ed. the EN'TER~ button is praised to set the program in the machine.
In the preferred embodiment, the oomQuter "snaps" the height of each bar to ones of a series of discrete values, In the case of sodium, these discrete values are apacxd is 1 mEq/I" steps.
Displayed oa the screen during this programming operation is a numeric data window in which the numeric counterpart to a particular bar may be displayed.
Whey the curve is first traced. the computer displays in this window the au~erical parameter corresQonding to each bar as it is defined. After the profile has been programmed, the numeric counterpart to any bar can be displayed by first touching a LOCK
button that locks 30 the curve, sad they touching the bar in questiat.
After the profile has been set, the user may wish to alter it is certain respects.
One way, of course. is to simply repeat the above.~dexribed programming Pr~ur''e. Another is to adjust the height of a particular bar. This can be accomplished in one of two ways. The first is simply to touch the bar to be altered. The height of the bar tracks movement of the 35 user's finger. The second way of adjustment is to first select a bar to be adjusted by reputedly touching (or pressing and holding) a Right Arrow button until the desired bar is highlighted.
('The Right Arrow button causes highlighting to scroll through the bars, left to right, and cycles back to the left-most bar after the right-most bar. The highlighting indicates the bar that is is selected.) The numeric parameter corresponding to the selected bar is displayed in the numeric data window. This value ~an then be adjusted by Up and Down arrow keys that cause the displayed parameter to increase and decrease, respectively. In the preferred embodiment, the Up and,Down arrow keys cause the sodium parameter to change in steps of 0.1 mEq/L, one-tenth the resolution provided in the original data entry procedure. A
similar ratio holds with other parameters programmed in this fashion. Again, the ENTER button is pressed to complete the programming operation.
As with other parameters, profiled parameters must also be Verified before they take effect.
After the above-detailed data profiling operations are completed, data corresponding to the programmed profile is stored in the computer's memory. periodically, such as once every fifteen minutes, a timed interrupt in the system's software program causes the computer to poll this memory for the value of the programmed parameter for the next time interval (here fifteen minutes). The physical parameter is adjusted accordingly using conventional adjustment mechanisms.
Once treatment has begun, the system only permits bar graph-bars corresponding to upcoming time intervals to be programmed. Hars corresponding to past time intervals reflect treatment history and cannot be changed. To readily distinguish past from future, the bars corresponding to each are displayed in different colors.
In all aspects of the interface, the user is guided from one touch to the next by a feature of the preferred embodiment wherein the button that the user is most likely to press next is highlighted. For example, when the machine is in Rinse.~ode and is nearing completion of these operations, the Self-Test button is highlighted, indicating that this is the 12a next likely operation. Similarly, when tie Self-Test operation is nearing completion, the Prime button is highlighted. By this arrangement, even novice users are easily guided through the machine's various phases of operations.
In addition to the above-described user interface, communications with the dialysis machine can also be effected by an RS-232C serial data interface 530 and by a data card.
Data cards (also known as memory cards or RAM cards) are known in the art, as represented by U.S. Patents 4,450,024E4,575,127,4,617,216.,4,648,189,4,683,371.,4,745,268,4,7 95,898,4,816,654,4,827,512,4,829,169 and 4,896,027.
In the preferred embodiment, a data card can be used both to load treatment parameters into the machine and to download logged patient parameters from the machine for therapy analysis.
Among the treatment parameters that can be provided to the machine by a data card are the ultrafiltration profile, the sodium profile, the bicarbonate profile, the blood pump flow rate, the treatment time, the desired ultrafiltration removal volume, the dialysate flow ~ ~.ri UJ'lJl tUJy) -l3-rate, the diaiysate temperature. the blood pressure measurement schedule and alarms. and the heparin Prescription. , Among the patient panuneters that are logged by the machine ~ ~ ~ ~
downloaded to a memory card for later theca PY ~lYsis are: temporal data relating to dialysam temperature and conductivity (both of which ane typically measurod at several points ~ ~
fluid circuit), v. ail. diaiysate, systolic and diastolic pressures. blood flow rate, total blood pro~ued. ulttafiltntion rate, total ultrafiltrate removed, the ultrafilttate goal. and the mine states.
Additionally, the data card can convey to the machine ~ c~ that. when head by the machine, initiate special op~ons. These operations include c~li>~ion m~
tedmicisa mode, enabling the blood prartrre monitoring function. modifying the patatneters tnm~aitted over the serial port for diagnostics. and others.
The card used in the preferred embodiment is commercially avaiLbla from Micro Chip Tochaologies wader the trademuh ENVOY and provides 32K of data storage in EEPROM form. Similar cards are also available from Datakey.
~ a ~ °°°~g tit parameters is read by the machine. the stomd patamaera do net immediately take effect. Inssad. each is displayed oa the mctnea sad the operator is asked, through p~pts that appear oa the sctaea. to verify each individually. If a parameter is not verified. that aspect of machine operap« is left unchanged.
In the preferred embodiment. the parameters loaded from a memory cad am displayed in.their respective parameter windows and each is highlighted in sequence, with the system soliciting verification of the parameter is the highlighted window. In alternative embodiments. a plurality of parameters are be displayed for verification as a group.
Returning now to FIG. 7, the computer system 500 that controls the user in~rfaca and other aspects of machine operations is built around as IBM-AT
compatible motherboard 502 that includes an Intel 80286 microprocessor 504 sad 256K of intet~naected by m AT bus 508. Into ezpansion slots is this motherboard plug seven additional boards: a memory bob S 10. an RS-232 board 512 (which is dedicated to controlling a patient blood ptrsaut~e monitor). as InputlOutput system controller board 514, an ultntfiltrationlptnportioning system controller board 516, a blood pump system controller board SI 8, a touch screen interface board 520, sad m EGA display adapter bosr,d 522.
The computer system has five primary responsibilities: (I) user interface (i.e., through the CRT display and the touch screen); (2) slam mine control (i.e.,rinse, prime, dialym, etc.); (3) microcontroller communicuioas; (4) conducting of xlf tests;
sad (5) calibrations. These functions are carried out by the AT-computer in conjunction with the above-listed ezpansion boards.

t Turning now to a more detailed description of each component, the memory .~ board 510 contains the firmware for the 80286 microprocessor. The memory hood can hold up to 384K of read only memory (ROM) 524 sad 8K of nonvolatile static random access mearory (RAM) 526. Also included oa the memory board is a memory interface 528, as RS-232C interface 530, sad s time of day clock 532. The interface 528 is conventional sad simply bindles the addressing of memories 524 sad 526. The RS-232C interface is for general propose use (as opposed to the RS-232 interface 512 that is dedicated to use with a blood pre:atre monitor) sad is typically used to t~emotely provide programvming iastructioas to, and to iate:rvgare patient treatment data from, the machine. The time of day clock 532 is used, inter alia, .to timddate stamp patient data as it is acquired and to provide a time of day rake by which sutomatod machine ope:uioas (such as uasueoded v~rarm-up) may be oontmued. - .
The host control program is written is the 'C' programming language. This code is compiled, linked sad loaded into the ROM 524. The purpose of the host control program is to:
(lather data from tha Iaput/Output, Blood Pump sad Ultrafiltrstioa oootroDer sub-systems. sad output c~vl tuacti~s to the various caaCroUer aub-I~ut data from the user iataface touch screen;
Monitor the data for violation of alarm limits and usage operating conditions, sad to set the appropriate Program alarm condition indicators;
Evaluate the data to daamine the current operating state of the control program, i.e.,Standby, Rinse, Self Test, Prime, and Dialyze; sad Update the display data to the CRT portion of the user interface.
The RAM memory 526 is used to store calibruion and machine parameters.
Ia order for the memory board to operate without conflict with the bast AT-adotheerboard, the motherhood must be modified by disabling the data buffers above address 256K. The memory c~troller's ROM space is mapped into the address spats from 256K to 640K. with the portion between 256K sad 312K being mapped also to address range 83ZK to 888K. The code st this upper address range is configured as a BIOS extension.
which results in the ROM being gives control by the motherboard's BIOS software following power.on initialization. Udike the stsadar~d BIOS extensions, the host code does sot redun to the BIOS
after being gives control.
Tha RS-232 board 512 permits computerized remote control of a patient blood pressaue monitor. Suitable blood pressure monitors that are adapted for RS-232 control are available from Spacelabs of Hillsboro, Oregon.
The touch screen interface board 520 is commercially available as part numlxr E271-400 from Elographics and is designod to operate with the E272-12 touch panel 501 that is - r w u:Jy~~ tUYHI
-IS-used is the preferred embodiment. The function of the interface board 520 is to translate signals returned from the touch screen into a data format suitable for use by the 80286 microprocessor 504. Terminate and stay rrsident software for driving the intes6ce board 520 is available from Elographics.
The EGA display adapter card 522 is conventional and provides RGH signals to the CRT display 503..
The three tnicrocontroller subsystem (the blood pump system 518, the ultrsfiltration/proportioning system 516, sad the 1/O system 514) are partic>siasiy d~ ~
the following disatssioa.
Blood Putno 8v~em ?he blood pump controller 518 is built using an Intel 8040. a>ic:ocontroller atsd is responsible for controlling or monitoring five subsystems. They are (1) the blood pomp; (2) the blood pressure measurement (arterial. venous and eapaasion chamber): (3) hepnia delivery: (4) level adjust: sad (5) ambient teatperature. The blood pump controller operates in IS conjunction with a blood pump power board (not shown) that controllably provides operating power to devices controlled by the blood pump caarroller.
Ia still more detail. the primary operation of the blood pump controller 518 is to supply power to the blood pump motor such that the puatp head will torn sad pump at a rate sdeaed by the operator.
The blood pump controller system coasisis of the following major com~poneats:
p~rifltion User parameter entry Host caatroller Software Speed Error Control Blood Pmp Controller Hardware Spood Error Control Bp p~ g~
Optical speed sensor Oa tnotoc shaft Motor Power Driver Circuitry Bp p~ g~
The operator eaters the dashed blood imp rate information oa the video screen (CRT) touch panel. The host controller (80286 microprocessor) converts this information to tha appropriate motor rate which it then scads to the Blood pump controller (8040) on the Blood Pump Controller board. The 8040 controller converts the motor rate information to as analog level. which is fed to a motor speed control 1C (LM291'7-8) oa the Blood Pump Power board.
Aa optical speed sensor is mounted oa the rear abaft of the blood pump motor, with an LED being positioned on one side of the shaft, and a photo transistor on the opposite t side. The shaft bas two holes drilled through it, with each hole being perpendicular to the shaft and to each other. This results in four optical pulses rxeived per shaft revolution.
This tachometer signal is monitored by both the LM2917-8 and the 8040 controller. The 1.M2917-8 provides quick responding spexd control by comparing the motor speed with the desired speed information from the 8040. The result of this comparison is as error signal which provides an input to the motor power driver circuit.
The motor power driver provides a +24 V pulx width modulated drive to the motor at a frequency of approximately 30 KHz This drive is cttnent limit protected, to prevent damage is the event of a stalled motor.
The 8040 compares the tachometer motor speed information with the dtxirnd speed commanded by the 80286 and corrects the level provided to the LM2917-8 accordingly.
1a this way the 8040 guarantees the ultimate accariacy of the pump. with the LM2917-8 circuit not requiring nay calibration. In addition, the 8040 can monitor for control problems. such as tinder speed or over speed, which may result from failures in the LM2917-8 or motor drive ci:cuitry.
The 8040 also monitors the motor speed independent of the tachometer signal nsiag the motor's back EMF. Periodically (every 0.5 second) the motor drive is turned off for spproximately 6 millisecond and the voltage at the motor terminals is measured. Though this does not resrtlt in as precise as iadicatioa as the tachometer signal. gross failures can be detenained. such as when the tachometer signal is lost.
Blood Pressure Measurement The blood pressure measucemarts include the venous. arte:ial and expansion chamber (for Singly Needle treatment) presarres. All three taeasurrmeat systems include identical hardware. Each pressure is sensed by a SenSym SCX15 gauge ceasing pressure ttaasducer mounted to the Blood Pump Power board. Each transducer is c~aected to a differential amplifier dexieaed to provide a measurement range from -400 to +600 mmHg.
The output of each amplifier drives an A/D input channel of the Blood Pump Control system, at which point it is converted to a 10 bit digital value. The calibntti~ of each of the pr~awe inputs is handled entirely in software, requiring that the design of each amplifier guarantee that its output remain within the A/D input range of 0 to +5 V over the input pres~rre ranges and over all component tolerances.
H~atrin Delive;rv Heparin delivery is accomplished by stepping s stepper motor which rotates the pinion of a rack and pinion taechaaism. The pinion movex the rack, and the mochaaical fixture is such that the plunger of the heparin syringe movex the same distance. The stepper motor is controlled by the 8040 microcontroller located on the: Blood Pump Controller board S 18. Wheat the opexator enters a dexired heparin rate in milliliters per hour (mL.lh) via the front panel touch screxn, the host 80286 microprocessor converts this information to the «. a i 1.J.7>.7~ 1 Ugly t t appropriate motor step rate and passes it to the Blood pump microcontroller.
The Hlood pump microcontroller outputs a motor step rate logic signal to the Blood Pump power ~
when the heparin motor power drive circuitry energizes the appropriate stepper a~ con.
The motor step rate logic signal from the Blood pump microcontroller 518 is also input to the I/O Controller board 8040 microcontroller 514. The I/O
micracoatroller monitors this signal to determine if the heparin motor is going the appropriate speed, If it determines that an overspoed condition exists, it disables the heparin motor via a disable line that goes to the Blood Pump Power board.
TLere are two optical sensors to provide ~iaformation about the state of the heparin pump. The disengage sensor detects ~ the front psael syringe holder arm is is the Sage P~iaon. The end-of stroke sensor detects whey the pinion is raised up on the :acic, °~ w~ the gear teeth are not meshed. This is as indication of as ovetpresa~
ooadition. The Blood Pump microcontroller monitors the state of these sensors and passes ~
iafocmadoa to the host 80286 microprocessor.
I~yel Aditt~~t The level adjust system allows the operator to change the blood level is the artaial and veaoas ~p . A level up and level down button exists for each drip chamber. The 8040 microcoatroller on the Blood Pump Controller board 518 monitors the button positi~s. When a button is pt~sed, a valve selects that drip chamber and power is supplied to the motor such that the pump head of a peristaltic pump rotates to apply a positive or negative pressure to the drip chamber. The software logic only accepts one button press at a time. If two buttons are pressed simultaneously, both are ignored.
The motor drive cir~cuitty is located on the Blood pump power Board. The ~r ~Y ~ even in the forward or reverse direction. A direction signal from the Blaod 2S Pump Controller Board, along with a pulse width modulated motor rate signal controls two bipolar half bridge taotor drivers. Both half bridge motor drivers receive the same motor rate signal. while the motor direction signal is high st one sad low at the other to determine the direction the motor runs. The half bridge drivers provide a 24 V pulse width modulated drive voltage of approximately 30 KHz to the motor.
~ Other details of the Level adjusts are described h~~ow.
Ambient Temoeratune Control ~ P~~ of the cabinet cooling system is to keep the internal temperature of the cabinet lower than the 50 °C maximum te~eraritn at which the elxtronic components are gttaraatoed to operate. (Most electronic components are rated to operate at 60 °'C, the exception is the solid state relay used for heater control.) A fan is located at the base of the cabinet sad exhausts the warm cabinet sir. An intake vent for the ambient room temperature is located below the CRT on the back of the machine.

The cabinet cooling system consists of the following major components:
~es~vtion Lion Cabinet Faa Base of cabittec Blood Pump Temperature IC Blood Pump Power Board ~ Misc I/O Temperature IC Misc I/O Elcctroaics Pwr Bd.
Software Faa Control Haas controller Cabinet Faa Drive Blood Pump Power Board The two LM35DZ temp«aatre ICs are located ~ the Blood Pump and Misc I/O Eletxronics power boards. 'Ibis IC outputs s voltage linear with temperaatre is °C
(10.0 mV/ 'C~. These tempaamre readings are input to the fan conorol software.
The fan control software always responds to the higher of the two t~paatures.
Typical values are as follows. At 46 °C the fan turns on is the low speed mode and at 48 °C it turns on is the high speed mode. Theca is a 2 °C of hyateresis at these threshold tenzperaturrs, i.e., the fan r~euuns to low speed ac 46 °C and turns off at 44 °C. In addition, at 60 °C a cabinet tem~ature alarm ors that results is the machine shutdown state.
Tha fan power driver is locsted on the Hlood Pump Power board. A motor rate signal from the Blood Pump Controller board determines the duty cycle of a 30 KHz pulse width modulated signal. This signal is input into a passive filter to provide s DC signal to the ZO motor.
UF/Prooortionine Control Svstem The ultrafiltratiodproportianing (UFIPROP) controller 516 is built using as Intel 8040 microcontroller and is responsible for controlling the systems associated with ultrafiltratioa and dialysate preparation. This controller operates in conjunction with an ultrafiltratioa/ proportioning power card (not shown) that controllably provides operating power to devices controlled by the ultrafiltrationlproportioning controller.
Si:t:ub~systetas are cmtrolled or monitored by the UFIProportianiag controller 516. They are:
a. Tea>peruure Control b. Proportioning Control c. Flow Control d. OF Removal Control e. Conductivity Monitoring f. TemQeruure Monitoring Temperature Control The UF/PROP system 516 controls the dialysate temperature by easbliag a zero voltage crossing solid state relay, which provides the power to s 1500 W
heater (item 18 is FIGS. lA and 1B), with a 5 Hz pulse width ttwdulated digital signal (heater-enable signal).

Y~. ! / t,'S93/ 10991 The duty cycle of the heater-enable signal is updated every 0.5 seconds with the sum of the past duty cycle and a temperature error correction value. The correction value is proportional to the difference between the desired temperature (stored by the host) and the me:attrnd control temperature (meaatrod immediately down ~ of the heater housing), The host-detec~mined desired temperatu,,e is calcui~ed using the user-enteand desirai temperature and the stable "B"conductivity probe (item 46 in FIGS. lA
and 1B) te~atune. If the stable "B"conductivity probe teura is different from the user-eatetnd desired temperuure by snore than 0.05°C, they the control temperature th~oM ~
to the UFIPROP coat~ller is updated so that the "B"conductivity probe temperadun w;u equal the user-earned desitnd Mature. Ice this way, the dialysate temperature a the ~B~
ooodtac~ivity probe will be adjusted so that flpw rate and ambient tempa:amre ~ effects on the ~B'c~ductivity probe tempe:ature (and the primary temperature. displayed on the video sctnen) will be compe~ated, 'This control temperature adjustment is performed a maximum of every S minutes.
~rtioninQ ontr_oi The UF/PROP system 516 controls the trate(s) , to water propot~~
ratios by wing the diaJysue flow rate, the 'A'trate flow rue. and the ~B"
cooxntrate flaw rste.
The "A"and "B"canaatrate pumps (items 22 and 40, respectively. in FIGS. lA
ZO and 1B) are copper-motor driven (each by a cam/follower) diaphragm pumps which deliver s calibrated volume of concratrate per stepper motor revolution. Their flow rates are controlled by controlling the speed of the stepper motors. The concentrate pumps are unidirectional sad utilize the proper actuuion of a throe-way valve for their intake and output pumping strokes, The intake stroke is synchronized by a signal that is generated by as optical interrupter season which senses a pin mounted on the cam of the pump assembly, Further details pertaining to the 'A"and "8"concsatrate pumps are described hereinbelow.
The UFIPROP controller 516 utilizes the fact that the stepper ~
Z00 motor steps per revolution (baween e~ z~on pulse) to check the concentrate pumps for stepping errors. If late or early syncht~oai~tion pulses are received then the associated error conditions arse reported on the scrnea during the Technician Mode of the machine (further details provided hereinbelow).
During the Rinse Made. the host determines the concentrate aeatmeat mode based on the "A"and "B"rinse port interlock informstion (further details provided hereiabelow). If the "H"concentrate line (FIGS. lA sad 1H, item 104) is not coupled to the "B"rinse port (FIGS. lA and 18. item 30), a bicarbonate trratmeat is initiated by setting the proportioning ratios and the conductivity alarm limits sppropristely.
Conversely, if the "B"
con~trate line is coupled to the "B"rinse port, as scetate t~~t is initiated (further details provided hereinbelow). Using the dialysate flow rate and the proport>cmyt~ ~ ~

host determines the associated concentrate Bow rates and stores the two conceatnte Pump speeds in the UF/PROP controller. The proportioning mode (for acetste or bicarbonate dialysis) cannot be changed is the Prime or Dialyze Modes.
The control of the dialysate flow rate is described in the following Flow Control section of the UF/PROP controller dexriptioa.
Flow Centre! , The UFIPROP system 516 ~b the dialysate flow rate by controlling the time bdweea the switching of the flow equalizer (FIGS. lA and IB, item 54) valves (provided that a:: -:
all the fluid within the flow equalizer chambers has bees eacchaaged).
The average flow equalizer voluma is calibrated (measu:ed) during the Calibration Mode. The time bawear the switching of the flow equalir~r valves (FIGS. 1A and I8. items 142-149)~is scaled by the imst (a~rding to the calibration constant) sad stored in the UFIPROP controller so thst the user catered desired dialysate flow rate is achiavod.
To guarantee the complete fluid transfer tolfrom the flow equalizer chambers (FIGS. lA and 1B, items 126.128) two flow sensors (FIGS. lA sad 1B, items 58.
59: described is further details herriabeiow) are located within tha fluid path to dated the absence of dialysate flow. The time at which both sensors detecx ao flow has bees defmed as cad of stroke. The cad-of-broke tinm has bees defined as the time betwe~ the moment as end of shake was ceased sad the desirrd flow equalizer valve switch time. Since the supply pump speed controls the iasvataaoous dialysate flow rate, the UFIPROP controller servos the supply pt>~ speed in order to maintain s consistent cad-of-stroke time.
Since the flow equalizer volume is calibrated and the cad-of-stroke time is controlled, the UFIPROP system 516 can acaua<ely control the dialysate flow rate to the user-eate:ed value.
1JF Removal Control The UF/PROP system 5 t6 controls the OF removal rate by controlling the tithe between the switching of the OF flow mgr valves (FIGS. lA sad 1B, items 142-149). The UFIPROP system Viols the accumulated OF volume by counting the number of OF
flow miser strokes.
Since the OF flow meter volume is calibrated (matstu~ed) in the Calibration Mode. the rate which the host (80286 microprocessor) pasties to the UF/PROP
controller (atmtber of seconds between valve switches) is scaled so that the user-catered OF removal rate is achieved.
Ia the sumo way, the user-catered OF removal volume is scaled by the OF flow meter's stroke volume to a number of OF man .strokes. The host passes the number of OF
atuer strokes to the UF/PROP controller. The UFIPROP controller will then switch the OF
flow meter valves sad decrement the stroke number, at the desired rate. as long as the stroke number is greater than zero. The host can they calculate the OF removal volume accutaulated - PC: C/ US93/ 10991 _?l_ bY kung the number of OF f)ow meter strokes reraaiaing, scalod by the stroke volume, from the operator-entered desired OF removal volume. 'The accumulated volume is displayed ' during the Diaiyu Mode. This value remains during the Rinse Mode and is clesr~od upon the entry of the Salf Test Mode.
In Rinse. the OF removal rate is 3.6 L./h and the video screen indicates no IJF
volume accumulated. During the Self Test Mode, no OF removal occurs except during specific self tests performed by the machines (no OF volumes is acctrmulatesd). Ia t6e prime Moda,~the OF t~emoval rata is set by the operator and is no grates than 0.5 IJh (ao OF
volumes is accumulated). During the Dialyzes Modes. the OF removal rata is set by thes operator and is limited to bavvaea 0.1 and 4.00 LJh. For OF removes! to occur in the Dialyze Modes the following oooditians must be met: .
1. A target OF volumes and a OF rata have been catered (or treatment time and target OF volumes hsve bees entered and a machine-calculated OF rsta is used).

2 The blood pump is pumping.

3. Tha target OF volume has not been nac)tod.
Conductivity Monitoring Conductivity is used as a masursmeat of the eloctrolyta compoa;tion of the dialyssta. Ca~uctivity is usually defined as the ability of a solution to pass electrical curroat.
Tha oondncxivity of dialysate will vary dun to the temperature and the elecxrolyta composition ZO of the dialysate. ..
Tha UFIPROP system maaira condu~ivity at two locations (caoduc~ivity probes) in the hydraulic circuit using alternuing-current r~esistanca measurements between each of the conductivity probes' electrode pairs. The two flow path locations are at the "A"
conductivity probe (FIGS. lA and 1B. item 38) and the "B"conductivity probe (FIGS. lA and 1B. item 46).
Ones elxtrode of each of the probes is stimulated with a 1 kHz ac voltage while the other is held at virtual ground (current sense elocttode). Two voltages are produced by the t~esistsace measurement circuit. The ratio of the voltages is proporaonal to the rtsistaaces of the respective probe. Tha raissanca of the probes has been modeled as a fitndion of temperature and conductivity. Since each of the conductivity probes contains a thermistor, the ter~erature at each of the probes is known. Using the model that was derived for the probes, the temperature measured at the probes. and the resistance measured at the probes the conductivity is calculated.
Each conductivity probes is calibrated during the Calibration Mode, at which time the resistance of each probe is measur~cd at a known conductivity and temperature (by the use of as external reference meter) for the scaling of the probe's base resistance in the relationship described previously.

_77 _ t The UF/PROP system 516 generates alarms from the measured coaduciivities at tlse "A"sad 'B'probes. Since these conductivity alarms are used to verify the proportioning ratios, the alarms are generated by testing the 'A'conductivity and the 'B'portioa of the total conductivity ('B' portion ~ 'B'coaductivity - 'A'coaductivity). The alarm limits are d~rmined from the coaceatrate treatment mode and are stored in the UF/PROP
controller by the host. Therefore only during a bicarbonate dialysis tratmeat would the host store a naa-zero espectcd 'B' conductivity portion. ., The host determines the concentrate t:rastaeat mode during the Rinse Mode by reading the 'A'aad 'H'riase port iaterloclc iaformatiorz. If the 'B'cott~eeatrate line is not as the "B'riase port, a bicarbonate treatment is initiated by netting the Pto~poruoniag ratios sad the condt:ciivity alarm limits appropriately. Corrveraely. if the 'B'conceauate line is ccxtpled to the 'B'rinse port. as acetate trcattaeat is initiued. Upon e~titiag the Rinse Mode the concentrate treatment mode is set for the remainder of the dialysis treatment (conceatszte trtstm~t mode is only adjusted is the Rinse Mode).
Temperature Moni 'ne The UFIPROP system 516 meaatm the dialysate temperature at three locations is the fluid path. The first location is directly after the 6ata (FIGS. lA sad 18. item 18) and this thermistor, the heater thermistor (FIGS. lA and 1B, item 20), is used for the priataty ttm~ature control feedback. The ae~tt two thermiscon (FIGS. lA and 1B, items 110 sad 124) are contained is the 'A'aad 'B' conductivity probes (FIGS. lA sad 1H, items- 38 and 46, respectively). These temperatures are used to tempaaatre~om~te the 'A'and "B' conducttvtty measur~emeats. The B"coaducttvtty temperature is also used to generate a backup high temp«ature alarm.
The temperature tnessuremeat circuit used throughout the machine consists of a voltage divider with a Thevenia Equivalent circuit of 3062Q is series with a 7.55 V supply. The voltage divider circuit whey cotsuected to the thermistor used is the temperature measurement system refaeaced to ground produces the voltage to temper>atre relationship of T('C) _ (3.77V-Vtemp)(12.73K °CN) + 37'C.
The tolerance oa the component paameters used in the tearperature ' measttretaettt system can be as great as 1096. therefore the Wapasture-to-voltage relationship must be calibrated. Calibration of the tempaadtre muwremeats is a two-point calibrs<ioa done at 30 and 40 °C. The calibration procedure results in a calibration constant for both the slope and the offset for each temperature probe/circuit.
In the UF/PROP controller the voltage described above as Vtemp is tueasured for the throe temp~re probes in its system on a scheduled basis (every 0.2 sa~ads for the 'A'aad 'B"temperatures and every 1 second for the heater tea>perature).

The temperature that is displayed on the video screen is measured at the primary ('dialysate') conductivity probe, located just before the bypass valve (see FIGS. IA and 1B), by the 1/0 controller.
Innut/Outnut C'~~r."i c.,~...,.
N~ ~~Y~~ are controlled or monitored by the I/O control system 514.
They are:
~ Air detector ~ Blood leak detector ~ D~1Y~ pyre monitor ~ H
~ P~ ~ars~ed monitor ~ BYp~ syuem and flow sensor ~ Conductivity t:»itor ~ T~mpaatune monitor IS ~ power fail alarm Air=
T6e air detector assembly utilizes a set of 2 MHz piezo crystals. One crysxai fimcxions as an ultrasonic transmitter and the second crystal functions as a receiver. The transaoitter and receiver are housed in separate but i~tical assemblies. There is s distance of 0.20 inch between these assemblies into which the venous blood line is placed during dialysis.
The emitter is driven by a 2 MHz squarewave that is derived from a crystal oscillator Iocsted on an 1/O Electrical Power board 536 that is connected to the I/O controller 514 by a ribbon cable. When them is fluid is the blood line between the crystal assemblies.
the 2 MHz signal is coupled to the detector assembly. The return signal from the detector assembly is amplified and rectified by two indepeadeat circuits also located on the I/O Electrical Power bond 536.
T6eae do output levels are monitored using two different methods. The first method is the software generated alarm and the second is the har~dwar~e geaaated ate.
software Alarm Detection ~Pri~r. s~. ,.
One output is fed from the I/O Electrical power board 536 to as A to D
converter and grad by the 8040 microcontroller on the IIO Controller board 514. This value is averaged over a 400 cosec time period and reduced by multiplying it by 15/16 and subtracting 50 mV (for noise immunity). This new value is they converted back to an analog level to be used as as alarm limit. This software generated limit is compared to the rectified do signal from the detector. The output state of this comparator is monitored by the on-board 8040.
When the unaveraged signal falls below the software generated limit for longer than a cslibratable time period, an alarm occurs. Sensitivity of the software alarm is 10 microlitrcs at 300 mLlmin blood flow.

Hardware Alarm Detection (Secondary Alarml The hardware alarm is redundant to the software generated alarm. 'Ibis alarm uses two coatparators on the IIO Electrical Power board 536. Oae cotnparacor looks for a minimum do level from the rectified detector signal which guarantees the presence of fluid in the venous tubing. The second cotaparator is ac-coupled to react to a large sir bubble is the tubing. Sensitivity of this detector is approximately 300 tnicrolitres at 300 tnL/tain blood flow.
Both cotapancor outputs sre wire OR'd together so that either comparator will generate as Blood Lcak Detector The detector assembly consists of a high-efficiency green LED and a photocell.
These components are installed into a housing through which spent dialysate passes. Both of these components connect to the IIO Hydraulic Power board. The LED is connected to a voltage-to-current converter on an IIO Hydraulic Power board 534 (which is also connected to the I/O controller 514 by s ribbon cable). The input to this circuitry comes from the I/O
IS Controller board 514. The photocell is tied to the +S V reference supply through a 750k ohm resistor. This provjdes a voltage divider which is monitored oa the I/O
Controller board.
The current through the LED is adjustable sad controlled via a D to A output from the I/O Controller board. The light intensity of the LED is adjusted to illutaiaata the pbotoall to s point whore its resistance is below the alarm threshold. During a blood leak.
the pt~esence of blood is the housing attenuates the light striking the photocell which causes as it>aease in both the photocell resistance and voltage. The increase in voltage (monitored by the microcontroller on the I/O controller board) results in a blood-leak alarm.
Further details on the blood-leak detector are provided herranbelow.
Dpi ],ysate Pressure Monitor The ditlysste pressure is sensed by a raisiive bridge prrssure transducer (FIGS.
lA sad 1B, item 64) located just upstream of the dialyzcr. The transducer is connected to a differential amplifier circuit on the IIO Hydraulics Power board 534 designed to provide a measurement from -400 to +500 mmHg. The differaatial amplifier circuit also has as offset input that cotaes from a software calibratable variable, DAC OFFSET. The output of the amplifier drives as AID input channel of the I/O Controller system, at which point it is converted to a 10 bit digital vahte. The calibration of the prGSSetre input is handled entirely is the software. requiting that the design of the amplifier guarantee that the output remains within the AID input range of 0 to +5 V over the input pressure range sad over all cotaponent tolerances.
Heparin PItmD Oversoeed Monitor To ensure that the heparin pump does not exceed its set speed, the IIO
controller board software monitors a clock signal from the Blood Pump Controller board that is equivalent to 1 /4th the heparin pump step rate. In the event that a heparin pump ovetspeod - . PCT/US93/10991 occurs, the I/O controller board disables the heparin pump via a hardware line that goes to the Blood Pump Power board and notiFes the host of the alarm.
To determine if the heparin pump is running at the correct speed, the time requirod for tea clock signals to occur is measured (and stored is variable HEPTIMER) sad compared against a minimum time period that is xt by the host (HP P MIN). If the .
measured period is less than the host set limit, a normal-speed alarat occurs.
The bast is notified of the normal-speed alarm and the heparin Pump is disabled via the hardware line to the Blood Pump Power board.
~ ~e PAP ~n ranges. the host resets the minimum time period, HP P MIN, and the LO controller waits for the first clock signal to- - resort the timer (this fast clock is not counted as one of the ten). In this way' the alarm logic is resynchtoni~ed with the PAP sipper motor.
The I/O controller board S I4 also monitors the total atnotmt of heparin deh~
in the high-spoed bolus mode. Whoa it receives clock signals at a rate faster than a predetermined speed. it asatraes the pump is operating in the high-speed mode.
It has a high-apeed counter. H SPD CNTR. that is set by the host. If more high-apeod counts act t~
ane m the counter, a high speed alarm occurs. The host is notified of the high-speed alarm and the heparin pump is disabled via the hardware line to the Blood Pump Power board.
~ Svstem d Flow Sen~r ~ bypass mode is initiated when a primary dialysate alum is detected by the I/O Controller board, when a redundant dialysate alarm is detected by the UF/PROP
Controller board 516. whey the host requests bypass. or whey the manual bypass button is pushed.
The bypass valve (FIGS. lA and 1B, item 66) is in the bypass position when deeaergiud. It is drives from the nominal +24 V supply with a straight on/off transistor control on the I/O Hydraulics Power board.
. To verify that there is not a failure in the bypass system, a flout, sensor (FIGS. IA
and 1B, item 62) located ups of the dialyzer and just downstream of the bypass valve checks for flow. If flow exists during bypass, a Bypass Fail Alarm is triggered and the machine is put in the safe. nonfunctional. Shutdown state. If there is no flow whey not in the bypass mode, a No Flow tdarm is generst~. (F~~, ~ls on the flow s~ am ptm,;~
hereinbelow. ) This flow sensor consists of two thermistors. The first is a reference thermistor used to determine the fluid temperature. The second thermistor uses thermal dilution to sense the fluid flow. The voltage outputs from the thermistors on the I/O Hydraulics Power board 534 drive A/D input channels on the I/O Controller board where they am converted to 10 bit digital values. A software algorithm in the I/O Controller code uses these inputs to determine the flow condition. The design of the voltage divider guarantees that the output remains within -?6-the AID input range of 0 to +5 V over the input temperaturelflow range and over all component tolerances.
Conductivity MonitorinE, The dialysate conductivity probe (FIGS. lA and 1B, item 60) comprises two S stainless steel probes inserted into the flow path just prior to the dialyzer. The drive signal for the conductivity probes is a capacitive-coupled squarewave geaasted on the I/O
Hydraulic board 534. This signal is seat to the conductivity probe and a monitor circuit. Both the monitor circuit and the return signs< are roctified and filtered. These do values are routed to UO Controller board 514 along with the temperature signal.
Oa the I/O controller board, the tem~rature, conductivity, sad conductivity refe:~e signals are i~ut to m A-to-D converter that is monitored by the on-board 8040 mictocoatmlier. ~ The microcoatroller calculstes the temperature-co~sated conductivity.
This value is rhea disp4yed oa the CRT as the vity is miUiSiemeas per centimeter (mS/cm).
Temperature Monitorine The thermistor (FIGS. lA and 1B, item 168) installed is the dialysate oooductivity probe (FIGS. lA and 1B. item 60) chaagea its resistance is rinse to changes in temperature. The values for dialysate coadu~ivity and tempetantre meastu~i at this probe are displayed on the CRT sad era used to geaaate the primary slums for patent safety. If either ZO value is outside preset alarm limits, a bypass condition and as audio alarm occur.
The thermistor is wired to a res~or divider network on the I/O hydraulic board.
The output of this divider network is seat to the Miscella~ous IIO controller board 514 where it is monitored by the on-board 8040 microconteoller via as A-to-D converter network. From this information, the controller calculates the temperature using offsu and gain pat$meters ZS stored in the boss from the calibration. Calibration of the temperature measurement is a two-point procedure done at 30 and 40'C.
Line Clame The line clamp opens with a solenoid sad clsmps with a spring retina. Whey the solerwid is not eaergizod, the spring pushes the plunger away from the solenoid. This causes 30 the plunger to claasp the blood tubing. Whey the solenoid is ~rgined, it pulls the plunger in widt enough fotze to overcome the spring fotre. This unclat~s the blood tubing. In the event of a power failure, the solenoid is de-energized causing the blood line to be clamped.
The solenoid is controlled by the line clamp board. On the line clamp board is a pulse-width modulated currait controller. This circuit applies sufficient carnal to the line 35 clamp solenoid to pull in the plunger. After pull ia, the controller ran>Qs the currant down to a level capable of holding the line clamp open. This cut-back in current reduces the temperature of the solenoid, tuvlting in a more reliable device. Also located on the line clamp board. is a quick-release circuit which helps dissipate the power stored in the solenoid.

-- . PCT/ L~S93/ 1099 I
7_ , The result of this circuitry is a quicker and more repeatable clamp time over the life of the machine.
Control for the line clamp comes from the Miscellaneous 1/O controller board S 14 via the I/O power board 536. The control signal for clamp and uaclamp is optically S couplesd on the line clamp board. 'Ibis provides electrical isolation between the high voltages usesd to operate the lines clamp and the: low voltages used for the control signals from the ~~pto~ssor.
Power Fail Alarm ... 'lies power-fail alarm circuitry is located on the Misc I/O Electrical Power board ..~ 536. and incledas a CMOS power state flip flop powered by a 1 Farad (F) ~~r. ~ ~p . flop, which can be toggled by either the front panel power button or the 80286 system .
controller. provides the following functions:
~ ~oever power is not suppliesd to the machine (i.e., when the +5 V
. tatpply is off) and the Sip flop is in the oa states, power is supplied frrim the 1 F capacitor to then audio alarm device. Whenever poorer is applied to the asachine, the flip flop's output state is randy by the 80286, which provides indication of the intesaded machine power states. Also. when then flip flop is is the on state, power is suppliesd to the front panel power tiwitch LED.
~ Thos first fiutction listed above results in the power fail alarm. Thes alarm occurs either if the trsachine loses power whiles it is running, or if tho front panel power button is pry "on"when theca is no power suppIiexi to the machine. The alarm can be silenced by toggling the; flip flop off via pressing "off'the front paned power button.
Refrxeace is made hexrin to seven appeodice"s (A - G) which form part of the specification hexoof and which further detail certain aspescts of the preferred embodiment.
Hyflass Valve Flow Sen~
30 The dialysis machine of the prexetst invesntion includes a bypass valves flow sensor which is utilized to confirm that dialysate flow to the dialyzer is completely interrupted during bypass. The bypass valves flow sensor comprises a first thermistor 202 and a sescond thermisior 204~ as shown schematically in FIG. 2. FIG. 2 also shows in siraplibod schematic form the flow equaliitr 54, then bypass valve 166, and s dialyzer 208. The first and second thetmistors 202, 35 204 are of a negative-temperature-coefficient (NTC) types known in the arc.
The first, or "sensing."thermistor 202 is energized with a 20 mA constant current wEuIe the sescond, or "reference." thermistor 204 is driven with a negligibly small curre;at.

_7$_ The electrical restscauce of both thermistors 202. 204 is measured using electronic circuitry (not shown). The resistance R(T) of each thernustor 202.204 at a gives temperature T is determined by the following relationship:
R('I7 _ (Kt) eap(-KZn where K t and K2 are constants. Hence, the thermistor resistance is a function of its Sincx the electrical power input to the reference thermistor 204 is negligibly stttall. the tezaperature of the reference thetmis<or 204 will be sul~taatially equal to that of the liquid surrottadiag it. war flowing or not, at all times. The sensing thermistor 202, on the other hand. is powered by a substantial constant current. Heave. the . seosiag thermistor 202 will undergo appreciable self-heating. During conditions of no dialysate flow past the thamistors 202. 204, such is during bypass, the tetapasture of the refernace thertttistor 204 IS will be equal to the temperaatre of the dialysate surrounding the reference thesa»or 204.
However, the no-flow tes»paawre of the sealing thertttistor 202, as a result of self-besting, will be :itbstantially greater than the tetaperantre of the refe:eace thertaistor 204. During conditions whey disJysate is flowing past the thermistors 202. 204. the ~pera<ure of the rr3fereace thermistor 204 will,again. be equal to the temperature of the dialysate. The ZO t~erature of the leasing thertaistor 20Z, while grauer than that of the reference thermistor 204, will be somewhat lower thaw the temperature thereof would otherwise be during no-flow , editions. This is because dialysue flowing past the sensing thermistor 202 will conduct a portion of the self heating energy away from the thermistor 202, thereby lowering the temperature of the thertaistor 202. The bypass flow sensor can detect flow as low as about ZS 3 taLmia.
Since the t;eosiag thamistor 202 is drives with a coastaat~urreat source. the amount of power input into the thermistor 202 is limited according to the tslatioaship P =
IZR. As a result, the ultitaate self-beating temperature achievable by the axasing therttustor 202 will self Iitait. thereby protecting the sensing therntistor 202 from a damaging thermal 30 ruosway condition.
The two thermistors 202, 204 are calibrated by measuring the electrical resistance aaoss theta individually under conditions of no dialysate flow at both 30 sad 40 °C. A
tttathetmtical relationship is utilirrd during calibration which equstes the resistance of the xasiag thermistor 202 sad the resistance of the rcfereace thertaistor 204 at say temperature 35 between 30 sad 40'C. If Rh(t) represents the sealing thermistor resistance at T = t, and Rr(t) represents the reference thertttistor resistance at T = t, then. at no dialysate flow. Rh(t) = A itr(t) + B. where A and B are calibration constants determined by the Ytr 1 / US93/ 10991 -29- s equations shown below (since lZh(30), Rh(40), Rr(30), and Rr(40) are measured during calibration):
Rh(30) a A i~r(30) + B
Rh(40) = A ftr(40) + B
Heave. if the thermistor resistaaces are equal. they the electronic circuitry (not shown) coupled to the thermistors 202.204 recognizes such equal resiataaca as iadiatiag a ~~
dialysate flow' condition. However. if the resiataaces of the first and second thermistora 202, 204 aro not equal, which occurs when any dialysate flow (grater than about 3 mlJmin) is passing by the first and second thermistors 202.204, the electronic circuitry recognizes a 'dialysate flow' condition. Thetrofore, whenever the machine is in bypass, if the electronic circuitry senses that the resistaaces acres the first and second thermistors 202, 204 is unequal, indicating flow, the machine will trigger as tIarm condition to notify the operator of failure of the bypass valve 66.
The advantage of the bypass valve flow sensor 62 as described heniaabove is that it aosbles the dialysate bypass valve 66 to be tested fuacxionally. i.e..via a determiastioa of whether or not the bypass valve 66 actually shut off the flow of dialysata to the diaIyzer 208.
This is the first known user of such a Bow sensor is a hemodialysis machine.
Other bypass valve sensors known in the relevant art merely test whether or not. for e~tampie. the bypass valve has beta energized. One example of such a mechanism is a sensor that determines whether or not a solenoid controlling the valve has shifted position in response to application of cxtrratt thereto. In the present invention, in contrast, the bypass valve flow sensor verifies that the bypass valve 66 has actually seatod properly, No-Ultrafiltntion-During-Bvoas~ Sensor This feature, shown schematically as item 70 in FIGS. 1 and 2. utilize a first sad a second thermistor 210, 212 in a meaner similar to the bypass valve flow season 62 discussed above. The first sad second thertnistors 210, 212 are exposod to dialysate flowing through conduit 174 just downstream of the dialyzer 208 but upstream of the bypass lice 166.
This feature 70 is utilized during automatic testing of machine fuac:ions, as controlled by the machine's microprocessor. During such a test. dialysate flow is bypassed from the dialyzer 208. The flow equalizer 54 volumetrically matches the volume of dialysata that would ordinarily enter the dialysate compartment (not shown) of the dialyzer 208 with the volume of dialysate exiting the dialyur 208. During bypass, the volume of dialysate passing through the bypass valve 66 and bypass line 166 is equal to the volume passing back through the flow equalizer 54 via line 158. Since the OF line 178 is occluded by the OF flow meter 76, any dialysate flow past the first and second thermisiors 210. 212 in either direction must be due to dialysate flow passing through the dialyur membrane (not shown) into the hluo~d compartment (not shown) thereof or from the blood compartment thereof into the dialysate compartment theroof. If such flow is detected, the machine triggers an operator alarm.
Automatic Testine of Ultrafiltration Function 'This feature is utilized during automatic testing of machine functions that occurs before the machine is used for patient treatment. This automatic test is controlled by the machine's microprocessor along with other self-test routines. One example of whey ulttafiltrstioa-fitac:ioa testing is automatically engaged is whey the machine is is rinse and producing dialysate without nay prevailing dialysate alarms such as temperature and 'vity. A complete aelf-test routine begins whoa the operator touchGS the "test' button on the touch screen before beginning a dialysis treatment. Ia order to test the ultrafiltruioa fuac:ioa. the dialysate lines 174, 206 (FIGS. 1 and 2) must be connected together. enabling dialysate to circulate therethrough without having to ~ttse s dialyzer.
Because a dialyur is not used, the flow equalizer 54 discharges a volume of dialysate into line 206 that is substantially equal to the volume of dialysate passing through line 174. Hence, a volumetrically closed loop is formod wherein dialysste exits the flow equalizer 54 through the outlets 156 thereof, passes through lines 206 and 174 coupled together. and rxattts the flow equalizer 54 through the inlets 154 thereof. Included is this closed loop is the OF flow man 76. The OF
flow meter 76 permits a discrete volume of fluid to be removed from the closed loop. Also included in the closed loop is the dialysate prmaue transducer 64.
2p To perform the test, the OF flow meter 76 removes about 3 mL of dialysate from the closed loop. This removal of 3 mL is suff-tcieat to tower the dialysate pressure measured at the transducer 64 by about 200 to 300 mmHg. If these are no leaks in the closed loop. this lowrernd pressure will remain substantially constant. The machine will monitor the depressed dialysate pressure for about 30 sxonds during which the pn~sure must remain within a ~ 50 mmHg limit of the initial low value. If the pressure rises and passes a limit.
the machine will trigger an operator alarm.
Automatic Setting of ProoortioninQ Mode A~~ t lnm, Connection of Concentrate L-roes As described hereinabove, the oonceatrate rinse fittings, e.g..the "A"nod "B"
rinse fittings 28. 30. rv~y (~GS. lA and 1B), are equipped with proumity sensors which -smse whether or not the corrapondiag concentrate Lines 94, 104. re~uvely. are connected thereto. Such information regarding whether or not a cottaattste line is coupled. to a c~re~pondiag rinse fitting is utilized by the machine's microprocessor to set the concoct proportioning mode. ~.g~.a~ or bicarboaate dialysis.
For e~tample. during the machine's "dialyze' mode. if the machine's microprocessor receives a signal indicating that the "B" conceatrste line 104 is coupled to the "B"rinse fitting 30. the machine will operste only the 'A'cortceatrate pump 22. If the "H"

- t'l.: l / l.'S93/ 1 U99 -31- , caaceatrate line 104 is not coupled to the "B"rinse fitting 30, the asachine will operate both the "A"and "B"concentrate pumps 22. 40, respectively.
Such connections of the "A"and "B"concentrate lines 94, 104 also dictate the proportioning ratio of "A"concentrate. During acetate dialysis, the volumetric ratio of "A"
canceatrate to dialysate is 1:35. During bicarbonate dialysis with Drake Willock braced concentrates, for example, the volumetric ratio of "A"concentrate to dialysate is 1:36.83.
Hetxe, the machine automatically adjusts the pu>~ing rate of the "A"concentrate pump 22 is to whether or not the "B"concentrate line 104 is coupled to the "B"rinse fitting 3p.
The prouimity s~ors are ahowa in FIGS. 3A sad 3B. FIG. 3A is as isometric de:pcxion of, for example, the 'A"and "B"rinse fittings 28, 30 situated on the right side 218 of the machine. On the annular surface 220. 222 of essch rinse fitting is as angled dep~orl 224, 226, respectively. As depicted in the right-side elevatiaoal view of the "A"rinse fitting 28 shown in FIG. 3B. beneath the angled depression 224 is s light-emitting diode (L.ED) 228 (shown schematically). A photosextsor 230 of a type known in the art is also situated bath the angled deprexsion 224. The LED 228 is energized with a pulsatile signal in the kilohertz ranges (so as to not be fooled by 60 Hz illumination). 'The LED 228 sad photoaeaosor 230 are ot;iexited such that light 232 from the LED 228 passes through a first face 234 of the angled depression 224. is reflected off an annular surface 236 of a connector 238 on the eazd of the "A"
cooceatrate lines 94, passer through a second face 240 of then angled depr~ion 224 to be sewed by the photose~sor 230. ' So long as the photosextsor 230 rxeives reflected light from the LED 228, the machine's microprocessor circuitry (not shown) 'interprets" such a condition as indicating that the "A"concentrate line 94 is coupled to the "A"rinses fitting 28. If the light 232 does not reflect so as to impinge the LED 230. the microprocessor circuitry 'interprets' such a condition ZS as indicating that the "A"concentrate line 94 is tmt coupled to the "A"rinses fitting 28 but is cauple~d to, e.g..a supply of "A"concattrate.
Prediction of Dialvesrr Conductivity The software controlling the operation of the machine's microprocessor includes a routine for predicting correct dialysate conductivity. Such predictions automatically refleset the particular brand of concentrate being used. since different groups of concentrate brands resquirs differextt proportioning to yield a dialysate having a correct ionic stremgth and edesdrolytic profile.
Various groups of concentrates are: currently marJceted. Theme include: ( 1 ) bicarbonate concentrates manufactured by Cobe (utilizable for variable sodium and variable bicarbonate dialysis sad intexrded to be diluted at a ratio of 1 part "A"concentrate to 1.43 parts "B"concentrate to 45 parts dialysate); (2) bicarbonates concentrates maaufacturod by Drake Willock (utilizable for variable sodium dialysis only sad intended to be diluted at a ratio of 1 part "A"concentrate to 1.83 parts "B"concentrate to 36.83parts dialysate); and (3) Acetate t cooceatrates inteadod to be diluted at a ratio of 1 part acetate concentrate to 35 parts dialysate. The machine is 'instructed" or programmed by a tochaician as to which brand of concentrate is being rued. Such programming is done using tlse touch screen with the machine is the "calibration" mode.
The sottwsre utilizrs a different algorithm for each group of concentrates and for acxtate or bicarbonate dialysis using cottceatrates within nay single group, to calculsie a baseline "calculated' cooduc:ivity value. Each algorithm roquires that certain data be eatand by the operator using the touch . For example, for bicarbonate dialysis, the machine will 'ask"the operator to eater baseline (i.e.,not adjusted up or down relative to a standard. or nao-variable, ptoportiaoing ratio) values for sodium and bicarbonate ion cottceatratiaas.
~S P~ P~g of the concentrates, the machine will determine a "calculated"
dialysate conductivity. Before begittaiag a dialysis treatment. whey the machine is proportioning conceatrata and producing dialysate at the proper teatpersture, the touch scrxa will display as 'acwal' dialysate conductivity value as maVatred by the dialysate caadu~vity probe 60 (FIGS. lA and 1B) and "ask"the to verify the corcectacss of that value against the value stated to be cornet by the coacenttae maaufactuttr on the concentrate label.
If the operator rinds that the displayed conductivity value is correct, the machine will spare the displayed "ac:;tai" value with the "calculated" value. If the "calculated" value is differatt from the displayed value, the machine will regard the displayed baseline vales as correct since the operator "told" the machine that the displayed value is correct. The machine will also calculate the ratio of the displayed baseline value over the calculatod baseline value and will multiply nay s<tbsequeatly determined calculated value during the dialysis tr~eatmeat by the ratio to obtain new "expected" conductivity values. For azample, for variable sodium dialysis, the operator will program the variable sodium profile to be delivered to a patient over the course of the upcoming dialysis treatment. Whenever the machine changes the sodium canceatratioa during the course of treatment as programmed by the operator, which accordingly changes the dialysate conductivity, the machine will codetermine a "calculated"
conductivity value and apply said ratio to determine a new "expected"
conductivity value. These expected conductivity values are used by the machine to calcWate and set upper and lower conductivity alarm limits at ~ 596 of the initial or adjusted "expected"
conductivity value.
For Cobe brand bicarbonate canaatrates, the calculated baseline dialysate conductivity is determined by the following algorithm:
calculated conductivity in mS/cm = [-.036 + 3.7z10s ((Na+] - 130)][HCOj ] + [14.37 + .101([Na+] - 130)]
where the operator eaters the baseline concentrations of sodium and bicarbonate using the touch screen.

w. m uay.~i w>W

For Drake Willock brand bicarbonate concentrates, the calculated baseline conductivity of bicarbonate dialysate is determined by the following algorithm:
calculated conductivity in mS/cm = .1038[Na''] - .54 where the operator eaters the baseline concentration of sodium using the touch screen.
For all brands of acetate coaceatrates, the calculated baseline conductivity of acwte dialysate is determined by the following algorithm:
. cal<atlated conductivity in mS/cm = .0895(Na~ + 1.41 where the operator eaters the baseline concentration of sodium using the touch screen.
For bicarbonate dialysis, the machine will also automatically set alarm limits around the conductivity masttrnd at the 'A'oondttctivity probe 38 (FIGS. lA
and 1B) in a similar aoanner. (Dtuing acetate dialysis. the conductivity at the 'A'conduciivity probe 38 is aqnal to the conductivity at the dialysate vity probe 60. so setting of alarm limits aronad the ooaductivity a the 'A'coaductivity probe is not necessary.) For bicarbonate dialysis. the atachine 'assumes' that the 'A'coaemtrate is being proportioned properly (at the cocroct proportioning ratio). based upon the operator having verified that the displayed dialysate conductivity value is corral. The machine determine a baseline "calculated' conductivity st the 'A'coaductivity probe based oa baseline sodium and bicarbonate vooceatrate iafotatsdoa provided by the operator via the touch screen. The machine they calculates a ratio of the actual conductivity as measured at the 'A'coaductivity probe 38 over the calculated conductivity at the 'A'conductivity probe. Then, whenever the machine changes the sodium concentration during the course of a dialysis trestmatt as programmed by the operator, the machine will determine a new calculated conductivity value and apply said ratio to determine a new 'ezpecied' conductivity value at the 'A'conductivity probe.
For Cobe brand bicarbonate c~,eatrates. the calculated baseline conductivity at the 'A'conductivity probe is determined by the following algorithm:
calculated conductivity in mS/cm = [-.110 + 9.7:1 Os ([Na+] - 130)][HCOj ] + (15.04 + .105([Na+] - 130)]
where the operator eaters the baseline sodium and bicarbonate concentrations using the touch screen.
For Drake Willock brand bicarbonate concentrates, the calculated baseline conductivity at the 'A"conductivity probe is dete:rained by the following algorithm:
calculated conductivity in mS/cm = .1114[Na+] - 5.90 S
where the operator eaters the beeline sodium concentration using the touch screen.
ControIlinQ Flow Eaualizer End-Of Stroke Time As discussed hereinabove. the Bow equalizer 54 (FIGS. lA and 1B) operates via a four-phax cycle. In the first and third phases, "pre" compartments 130. 132 and "post"
compartments 134, 136 alternately fill and discharge their conceals. In the second and fourth phases, the valves 142-149 controlling liquid ingress and egress from the "pre" and "post"
chambers aro all is the off position for about 125 mast. During these brief socond and fourth phases, therefore, ao dialysata is flowing to the dialyur.
Preferably, at the beginning of the :stood and fourth phase. the diaphragms 138, 140 wiU have already racked end of stroke. Further preferably, the diaphragms 138,140 will have racked end of stroke st the same instant.
Eod of stroke is the moment when. for example, the "post" compartment 134 has reached a coarpletely full condition during a pluue after starting from a completely empty oonditioa a the start of the phase. 1a aeeordaace with the above, it is preferable, for example.
that the filling of the "post" compartment 134 reach end of stroke at the lama instant as filling of the "pre" compartment 132 during a phase and that filling of the "post"
compartment 136 teach end of strnlce at the same iauaut as filling of the "pre" compartment 130 during a dif~at phase. Such simultsaoous r~eachiag of end of stroke eliminstea ultrafiltratiora inaccuracies that otherwise could result if the "pre' and "poet' compar~nts (e.g.,130 and 136) being, say, filled during a phase are not filled at exactly the same rate.
Since valves 143, 144,146, sad 149 all tuna on at the lama instant that valves 142, 145,147, sad 148 coca off, sad vice versa, sad since each pair of compartments 130,134 and 132. 136 have exactly the same volume, it is possible to have pairs of compartmeata (130, 136, sad 134,132) reach end of stroke at the same instant. However, assuming that each chamber 126. 128 has exa<xly the same flow restriction thaethrottgh, achieving simultaneous end of stroke requires at least that presnrrrrs at the idets 154 be matchod sad that pressures at the outlets 156 be noatched.
To achieve such pressure matching, the idets 154 are provided with as input pr~esstrre equalizer 52 sad the 156 are provided with as output pressure equalizer 56, as shown is FIG. 4. The input pt~ssure equalizer 52 is coa>Qrixd of a flexible diaphragm 246 separating first sad ascend enclosed cavities 248, 250. A stem 252 is attached to the ceata of the diaphragm 246 and terminates with a flow-r~ricting elettxat 254. The output pr~re equalizer 56 is likewix comprised of a flexible diaphragm 256 xparating first sad second enclosed cavities 258, 260. Eateading from the center of the diaphragm 256 on both sides thereof arse stems 262. 264, each terminating with a flow-restricting element 266, 268.
Dialyses from the supply pump 42 flows unimpeded through the second cavity 250 oa into a "pre" compartment of the flow equalizer 54. The first cavity 248 passes dialysate from the dialyzer to a 'post" compartment of the flow equalizer 54. The first cavity 248 is also v..m.J~J/ 1V>YI
r part of a loop including the dialysate pressure pump 72. 'this hydraulic configuration has bees found to maintain identical pressures and therefore identical flow rates at the inlets 154 of the flow equalizer 54.
With respect to the output pressure oqualiur 56. when the pressure is equal is S both cavities 258, 260. the flow rates through each is identical. When the pressure. say. in the first cavity 258 exceeds that in the second cavity 260. the flow-restricting element 268 impedes flow into line 150, thereby incrasiag the pr~~ ~ ~e ~d cavity 260. 'This hydraulic configurstion has been found to maintain identical pressures and therefore identical flow rues at the outlets 156 of the flow equalizer 54.
'Therefore. since pressures and flow rates are identical as described above, both diaphragms 138..140 (FIGS. 1A and IB) come to, end of stroke at the same time..
The time required to attain end of stroke can also be controlled. The dialysaoe flow rate is set by the operator using the touch screen. This flow rate determines the shin frequency of the valves 142-149. The higher the dialysate flow rate, the more frequently the valves 142-149 shift. However, a machine maJfuaction or occlusion of a hydraulic line could .
cause an excessive ead-of stroke time for one or both diaphagms 138, I40.
~ dis~ed hereinabove, flow seasons 162,164 (FIGS. lA and 1B) are provided at the outlets 156 of the flow equalizer 54 for verifying when the diaphragms 138,140 have trashed end of stroke. When a diaphragm 138 or 140 has reached end of stroke.
the corresponding flow sensor 162 or 164, respectively, surds a no-flow signal to the microprocessor. The flow sensors 162. 164 are each comprised of a reference and sensing thermistor (not shown) and work in a meaner similar to the bypass valve flow sensor 62 and sensor 70 discussed hereinabove.
If the valves 142-149 receive a si_snal from the microprocessor to shift before the -Bow sensors 162. 164 have detxted end of stroke, the valves are prevented by the microprocessor from shifting until the ead-of stroke sigtul(s) are received by the microprocessor. In the event of an excessively long end-of-stroke time, the microprocessor Niters an increase in the pumping rate of the supply pump 42 to speed up the time to end of stroke.
Controlling the end-of stroke time not only incrases the OF removal accuracy of the machine but also keeps dialysate flowing through the dialyzer as much as possible to maintain the desired osmotic gradient therein. and easurns accurate proportioning and mixing of concentrates with water to form dialysate.
Timed Made Initiate Fmm Pr,.._.~.~_~
The microprocessor programming as described herein can be conventionally implemented to accomplish a timed mode initiation from a power-off condition.
As is known in the art, machine disinfection, rinsing, and "coming up ~ on concentrate and temperature to produce dialysate in a condition to beEin treatment are burdensome tasks that typically must be performed before the start of a treatment day. In large clinics having multiple dialysis machines. performing these tasks manually can require a substantial expenditure of time and other personnel resources.
The electronics of the machine are continuously powered, even whey the machine is 'off,'Staless the mains switch has been turned off or unless the machine's power cord is unplugged. As a result, the programming is readily adapted to include usa of the key pad splay on the touch scrxa by the operator to eater the desired time at which certain deaigaatod machine fttactions are automatically initiated. These functions include disiafectioa ..~ (such as heat-cleaning). rinsin8, and beginning the production of dialysate at the desired t~paature and ionic strragth for dialysis treatment.
Preservation of Machine Parameters During Brief Power-0ff The hemodialysis machine of the preset invention is provided with a battery back-up which preserves certain operational parameters previously catered by the operator is the event of a temporary power intaruptioa (less than about 20 minutes). Upon rrstoratiaa of power. the machine is is the stand-by mode.
All of the following parameters are saved is static RAM every 30 seconds or upon nay major change in machine state. Upon restoration of power after less than 20 minutes after the last 'time stamp' (time at which parameters were saved) by tha machine. the following parameters are restored:
Temperature corrxtion Accumulated OF volume removed Desired OF removal volume OF removal rate OF override flag Currnat machine state Previous machine state Self-test pass/fail flag Time .stamp Pr~xibed dialysis time Elapsed treatment time Preacxibed or elapsed treatment time ~P~Y ~8 Manual or calculated OF rate display flag Heparin pump rate Accumulated blood Accumulated heparin Alarm window limits for conductivity, temQaaatre, prescribed treatment titae, heparin, etc.
Profile settings for variable sodium and bicarbonate ~ m-m uJy~i W ryt r _37_ s Upon restoration of power, the "dialyze' mode can be restored by the operator touching the appropriate 'button" on the touch screen.
Drip-Chamber Level Adjusters As is known in the art, hemodialysis treatment requires use of as eattracorpoteal blood-line set. Blood-line sets are available fmm a number of manufacturers in a variety of differertt configurations. Virtually all blood-line sets have at least a vemous drip chamber.
Usually. as arterial drip chamber is also included. The drip chambers serve atvexal fttactiaos, including providing a means for removing air sad foam from the extracorportal blood before the blood is returned to the patient, sitd providing conveaiemt sites at w6iedt eotracorp~eaL
arterial and venous blood pras<tre exn be measured.
. A portion of the eactracorpor,eat blood-line set, including drip chambers, is normally fitted to the fitnnt of a hemodialysis atachine in an orderly and coaveaiemt arrangement using special clips and the like. Each drip chamber typically includes a short tubing segment terminated with a female fitting of a type known in the art as a Leer fitting.
IS The female Luex is adapted for c~nection to a male Luer fitting on or near the front of the machine. thereby providing the requisite connection of the drip chamber to a presstue-measuring component in the machine.
Drip chambers must be provided with a means for adjusting the blood levd ~~ P1Y m ~ that the blood levd does not drop so low is the drip chamber ZO that air becomes re-entrained in the blood. Dialysis machines as curtratly known in the art require that the operator manually rotate; one or more knobs on the machine to rotate a peristaltic pump couplesd to the: cors~poading drip chamber. Such a manual opexuion has proven to be a cumbersome annoying task. especially since the peristaltic pumps can be difficult to rotate.
25 The machine of the present invexttion overcomes this problem by providing, as shown schematically in FIG. 5, an dectrically driven reversibie positive-displacement pump such as a pexistaltic pump 272 which replaces the hand~petsted peristaltic pumps fo<m~d on conventional hemoeiialysis machines. The perisVltic pump 272 is fitted with fIe:ibles tubing 274, one end 276 of which is open to the atmosphere. The opposites end 278 is catplesd in parallel 30 to an "artexial" valves 280 and a 'venous"valve 282 coupled to an arterial drip chamber 284 and a venous drip chamber 286, rapecdvdy. The valvex 280, 282 are preferably solenoid valves of s type known in the art. Each drip chamber 284. 286 is couplesd via a correxponding Luex fitting 288, 290 to the corresponding valve 280, 282. Included upstream of each Luex fitting 288. 290 is a pressure-measuring device 292. 294, such as a pressure transducer, which 35 commuaicstex with the microprocessor (not shown).
On the front of the machine are arterial and venous "up"buttons 296, 298, respectively, and arterial and venous 'down"buttons 300, 302, respectively, which control operation of the corresponding valves 280, 282 and the peristaltic pump 272.
For example, pressing the arterial 'up" button 296 opens valve 280 and initiates rotation of the peristaltic pump 272 so as to raise the blood level in the arterial drip chamber 284.
Pressing the arterial "down' buuon 300 opens valve 280 and initiates as opposite rotation of the peristaltic pump 272 so as to lower the blood level in the arterial drip chamber 284. The venous "up" and 'down' buttons 298, 302 operate in the same way to control the blood level in the venous drip chamber 286.
In intt Dialv~te Fiow Velocity Throueh the Dialvur Without Increasing Dialysate Flow Rate Most hamodialyzers ctureatly is use are hollow-fiber types which generally have a toots coatpact shape than parallel-plate or coil dialyius used previously.
Hollow-fiber dialyners as known in the art typically comprise a boodle of fine hollow fibers, each fiber made of s acmipermeable membruse material, erased in an outer cylindrical shell.
The shell defines a space surrounding the fibers termed the "dialysua compartment' through which flows the dialysste prepared by a dialysis machine. The pati~t's blood is conducted through the luaxas of the hollow fibers, Propelled by a blood pump as the dialysis machine.
Cka:aace of medbolic solutes from the blood through the fiber membrane to the dialysate depends on a number of factors. including the osmotic gradient scross the semipermable membranes. The osmotic gradient is de~adant on a number of factors including ionic strength and ionic profile of the dialysate, dialysate flow rate through the dialysste eomp:rtmatt, and flow dynamics of the dialysate as it flows through the dialysste oo~partmeat.
It is important that the dialysate flow rate be high enough to expose the fibers to a su~cient supply of fresh dialysate to effect satisfactory clearance of tonic solutes firm the patient's blood at a satisfactory rate. Any dead spaces or areas of blockage in the dialysate computmatt which are not e~zposed to a continuous supply of fresh dialysate will adversely affoct cleatsace. Such dead spaces can ba Induced by merely increasing the dialysata flow rate.
Howover. increasing the dialysste flow rate also increases the rate at which expensive dialysate co~atrates are consttmod. Therefore. it is advantageous. especially with large dialyzecs, to ire dialysate flow velocity through the dialysate comq~aritnent without necessitating a cott~espontiing increase in net dialysate flow through the dialysste compartment.
Aa embodiment of the dialysis machine of the prrsant invention solves this problem by incorporating a dialysate recirculstion pump parallel with the dialyner as shown tically in FIG. 6.
FIG. 6 depicts a typical hollow-Ether dialyzer 208 having as outer shell 306 defining a dialysate compartment. Extracorporeal blood is pumped by the machine's blood pump (not shown) through an arterial blood line 308 from the patient (not shown), through the hollow fibers (not shown) of the dialyzer 208, they returned through a venous blood line 3I0 to the patient. FIG. 6 also shows the "arterial" dialysate line 206 and "venous'dialysate line 174 ' , m. w uJy~i t urJ t ( also FIGS. lA cad 1B). A dialysate recirculation pump 312. such as an electrically driven gear pump, is coupled to the dialysate lines 206. 174 parallel with the dialyzer 208. The pump 312 can be driven with a variable-speed controller to adjust the pumping rate of the pomp 3I2 .
teluive to the flow rate of the dialysate as delivered by the dialysis machine (not shown).
By rocinculatiag a portion of the "spent" dialysate from the "venous"dialysate ~:.
174 to the "arterial" dialysate line 206 for r~epassage through the dialysate cotnpartmeat 306, the flaw velocity of the dialysate through the dialysate comparami';at can be increased without ~8 a ~~ndin8 increase in dialysate flow. Hence, it is possible with this fdt~e to improve clearances with a particular dialyzet without increasing the coaatmption of expensive dialysste conceatrstes.
Blood-Leak Detector Virtually all dialysis machines is curnat use employ a blood-leak detecxor to.
monitor dialysate flowing from the dialyzer for the presence of blood that might have leaked from the blood compartment into the dialysate compartareat of the dialyzer.
Most dialysis machines currently in use are capable of delivering only a fixed rate of dialysate flow, usually 500 mL/min. The blood-leak detectors on those opt with a detection sensitivity that is set at a fixed level and not c6aagod during the cmtrse of rmating a patient or eves a series of patients. At a dialysate flow rate of 500 mLlmin, many caaveatianal blood-leak detectors are set to detect blood having a 25 96 hematocrit flowing at ZO 0.35 mUmin into the dialysste.
The dialysis machine of the prexat invetstion is c~le of delivering dialysste st flow rates ranging from 500 to 1000 mL/min. adjustable in 100 mL/min increments. At various dialysate flow rates, a fixed leak rate of blood from the patient will be diluted a different amount by the dialysate. Therefore, a blood-leak detxtor having a fixed sensitivity level enabling it to detect a small blood leak in dialysate flowing at 500 mLJmin may not be able to detect the same blood leak in dialysate flowing at 1000 mL/min.
The dialysis machine of the present invention is provided with a blood-leak detector 78 employing a green LED 194 and s photosensor 196 (FIGS. IA sod 1B).
(A green LED is used hawse of the strong absorbance of groea light by red blood, yielding a greater in the blood-leak detector between the presence and absence of blood.) The blood-leak detector has a sensitivity that is automatically adjusted in a proportional manner to cease a gives leak rate of blood into dialysate having any dialysate flow rate between the 500 to 1000 mLJmin adjustability range. Such automatic adjustment of the blood-leak detector sensitivity is performed .by the microprocessor in response to the operator selecting a desired dialysate flow rate. The microprocessor adjusts the blood-leak detector sensitivity by altering the illumination level of the LED 194.

Calibration Scheduler and Data L.oeEer And Warnine Message i.oe~,,e,~,~
The dialysis machine of the present invention has a technician-activatsble 'calibration" mode and is programmed to permit entry of calibration data, dates oa which cataia calibrations or adjustmeacs are performed, cad dstes oa which a particular dialysis cater may desire to have certain calibrations or adjustments performed. The machine also automatically logs warning messages that can be of atbstantial help to a techaiciaa servicing the maehina The cslibratioa mode can be activated by ttuning ats an internal calibration switch. Whoa the calibrations arc completed. the machine is tetttmed to the opetstiaoal mode by forcing off the internal calibration switch, cad rrstartiag the machine using the mains power switch. Upon catering the, calibiatioa mode, the touch scrap displays tables of various calibtatioas cad makes provision for the opesuor to eats data or dates perniaing to nay of the listed calibraaoas.
The machine includes a number of ~ooeat monitors which are used by the mter~oprocessor to note cad 'tnoord' taadmts whaem the tespecave comg~oaeats eatpauacx .aa operatiaaal anomaly of iaWes< to a machine techaiciaa. For example, the 'A'aad 'B' ptoporti~ing pumps 22, 40 (FIGS. lA cad 1B) are each drives with a stepper motor 90,114, t~pectively. The stepper motors 90,114 utilize 200 'steps' per revolution of the motor shaft.
Tha stepper motors 90, 114 are provided with optical encoders by which the macltiae's microprocessor not only accurately monitors cad controls the rate of coaceatrate delivery, but also monitors stepper motor operation. If the stepper motor experieaxs one full rotation per 190 'steps,"the microprocessor will 'note" and log this anomaly, even if no adverse effect on dialysate conductivity resulted therefrom. A list of warttiag messages is provided below. In the list, system names above groups of messages are for reference only. Messages having parentheses indicate software functions. While actual faihtre of such functions would not be ezpect~ to occtu daring machine operation, the messages were useful while debugging the . software. Messages having particular value to the tecbniciaa, especially for troubleshooting mechanical malfunctions, are denoted with as astaislc.
' BLOOD PUMP SYSTEM
'ilkgd qlea in BP 7CMTT' 'Blood Pump Low Speed' 'BP Control Shutdown' *
'BP Command Error" ' 'Blood Pump Overspeed Alarm' 'Bld Pmp Ovaspeed Alarm' 'Illegal index in by xmitQ' 'Illegal index in by input()' 'long timer error' w-W .J7J/1V>yt -i l -UF/PROP SYSTEM

'Too much time between EOS signals"

'Early EOS detection' *

'UF SHUTDOWN' 'UF Command Error' 'UF Time scheduled Event Error' 'Unidentified Error is MISC
ERRFLG' _ 'A 1~ Noise' 'A Pump Missed Steps' *

'B Pump Noise' "B Pump Missed Steps' 'C Pump Noise' * (for three 'C Putap Missed Steps' * ~ ~s~) 'A temperature probe error"

"B t~rantre probe error' IO SYSTEM
"illegal qlen in IO XMTI"
'IO XMTT: bsd slat chage Ad.9bd' 'Illegal io_xmit() index' 'Illegal index is io input()"
'Illegal rode: in ioport xmit()' IOPORT SYSTEM
'No 8?SS...port terminated' "Set~wr state: hw ver=1' 'Setter state: hw ver=2' 'Set_povver -state: Can't power on' -'Set~ower state: Can't power ofl' 'Converse: illegal return from uccomt7' "Switch failure is reset~ortQ fuacaoa"
'Command buffer full in add_cmd()' 'Unrecognizable command in make cmd()' 'Illegal number of data bytes in make cmd()' 'Illegal number of data bytes is make cmdQ' The OF profiling feature according to the present invention provides the operator with a method for programming a OF profile that can vary over time during a dialysis treatmau to achieve a target OF removal volume. This feature is similar to variable sodium and variable bicarbonate features discussed heninsbove.
Specifications of the OF Profiling feature are set forth is Appendix A.
A detailed description of the user interface pertaining to the OF profiling feature is set forth is Appendix B. ' Having described and illustrated the principles of our invention with reference to s preferred embodiment. it will be apparent that the invention can be modified in arrangement and detail without departing from such principles. Accordingly, we claim as our invention all such embodtmeats as may come within the scope and spirit of the following claims and equivalents thereto.

OF PROFILING SPECIFICATION
APPENDIX A
APPLICATION OF GROGAN ET AL.

~ w-.. v.7~.Ji W i>t -'~3- s Sctoea Operuion:
Whey the Target OF meter is touched from the Prime or Dialyze screens. s new set of buttons will appear on the right side of the display, referred to as the OF screen.
The buttons will be labeled MAIN SCREEN, TARGET UF. BLANK, OF DATA REPORT, PROFILE UF, BLANK
(RESTART PROFILE), and BLANK (Verify). The functions for each button will lx as follows;
OF Scrxn MAIN SCREEN - Reduns to main Dialyze or Prime sctaea.
TARGET OF . Brings up the calculator for Target OF entry.
DATA REPORT - Brings up a data report with OF parameters.
PROFILE OF - Briaga up the profiling graph and buttons.
RESTART PROFILE -Bcings up the profiling graph and huttoos with the previous profile after a tr~eatmeat change.
Note: The Target OF window is accessible only is Prime or Dialyze modes.
Whey the PROFILE OF button is touched. a new set of buttons will appear on the scrxa, ZO tsferred to as the OF Profile Screen, and the profiling graph will overlay the main screen. The buttons will be labeled LAST SCREEN, GRAPH UNLOCK/VERIFY (dual function), OF
ONLYIVERIFY, SET CALC PROFILE, SET AVERAGE PROFILE, TEMPLATE PROFILES, and BLANK (Verify).
the RESTART PROFILE button will appear ody in Dialyze mode after the user entered profile has bees aborted by one of the following events; Target OF changed, Treatment time changed, OF rate changed manually, or OF rate set to minimum dun to an alum. When touched, the OF
Profile screen will appear, as whey the PROFILE OF button is touched. Ia addition. the graph will ba initialized to the przvioua verified profile.
The functions of the OF Profiling Screen buttons will be as follows;
OF Profiling Screen:
LAST SCREEN - R~ ~ ~ .
GRAPH UNLOCK - Unlocks profiling graph.
GRAPH VERIFY - Lock graph if profile meets target UF. otherwise btitt~s up Profile Adjust scrxa.

SET CALC PROFILE - Sets a coostaat OF profile at a race which will reach target OF (must be udocked).
OF ONLY - Enables the graph for OF Only profiling (must be ~~):
. _ OF ONLY VERIFY -Locks the profiled OF Only segments.
,. SET AVERAGE PROFILE - AvehgGt' entire trtat~eat profile~with s-straight line bdweea the first uncompleted time segment and the last time segment of the treatment (must be unlocked).
TEMPLATE PROFILES - Brings up the template profile screan.
The minimum initial entry prior to OF pmfiliag will be the treatment time and target UF. Thex will be antaed vis the calculator.
If the prssctibed treatment time is not set prior to graph operation. the message TIME NOT SET
will be displayed is the lows: left head corner of the psph. If the time is set and the target OF
volume is not set, the message TARGET OF NOT SET will be displayed.
~ lion:
The graph will have a vertical uis scaled for 0 to 4.0 Liters/hour with 0.1 L/h resolution, indicating OF removal rate. The horizontal uis indicates treatment time sad will be scaled for 0 to 6.0 hours, in 15 minute intervals.
.. A highlighted bar oa the Y-axis will indicata the OF rate limits. A similar highlighted bar oa the X-ruin will indicate the prescribed treatment time.
A graph mode indicator will display the alta:aste of the GRAPH LOCKIVERIFY
button.
It will be located in the lower right of the graph, displsying GRAPH MODE: X, when X is LOCK or UN-LOCK.
A:rows at the top and bottom of the graph will indicate the current active touch zones within the graph. Above the top arrow will be a number indicating the current OF rate for that time segment.
Each time xgmeat will have a marker which graphically indicates the removal rate fot that segment. While the graph is ualockod, touching a location oa the graph between the muimum ~ ~-W :JyJ/ IUyyl S
and minimum OF rates will cause the marker for that segment to a~rove to the location of the touch. While the graph is in the locked state. a continuous line will join the xgmeat markers sod the markers wiU not move.
The profiling segment size is selected in calibration to 15, 30 or 60 minute intervals. For segment sizes other thaw 15 minutes. the individual markers and touchzoaes for each 1S minute time interval will operata collectively.
The xlectable segment sirs wiU be added to the Sodium and Hicarbaaata profiling options for overall machine consistency.
Three OF volume indicators will be displayed at the top of the graph:
- TARGET: This will indicate the catered target value.

- PROFILED: This will indicate the calculated volume ted by the profile st any Vie. updated each time a xgment is altered. It will be used for comparison to the target volume while catering the profile, and when the GRAPH VI~tIFY button is touched:
- REMOVED: This will show the actual calculated OF volume removed during the ttracmeat, up to the curr,eat time.
Whey the prescribed time and target OF have been set. the profiling graph will initially be set to a constant rata which will meet target OF over the prescribed time. This will appear as a straight horizontal line. It is intended to be a guideline, to assist the operator in relaxing a profile that will meet the target OF volume.
. At this dme the operator has three options to select a OF ptv6le. The first two options involve tnanuslly adjusting a profile. The third Option is to recall a predesertained profile template, which is described is the neat suction.
To manually select s profile the operator can touch GRAPH UNLOCK, which will remove the line from the graph and enable user profiling. 'The operator has two options at this point, to profile OF rate for each time xgmeat manually, or to set the stating and/or ending points of as average rate.
SUBSTITUTE SHEET (RULE 26) f . ; Avenge Method: The user can choose as averaged straight line profile by touching a graph ~:::x, ~ ~. ::.location within the first and/or last time segments. Then by touching the SET AVERAGE
PROFILE button, the remaining segment markers will be positioned is approximately in a straight line baweea the ctartiag and ending markers.
. Manual Method: By tortchiag the graph at various points within the OF rata and treatment time limits. the user can 'draw' a profile for the satire tnatmeat. As the profile is dsswn, the PROFILE value at the top of the graph will update co~iauousiy. This will assist the oQaator is a::~- .. ~pag a profile that will come close to t~at~ag the target UF.
Onoe a profile has bees selecxed through one of these mahods. the operator will touch GRAPH
VERIFYY. At this time the total profiled volume. of PROFILE values will be compared to the target OF volume. If a difference exists, a new set of butts will appear oa the scr~eea. Their labels will read LAST SCREEN. BLANK. ADJUST PROFILE. ADJUST TARGET. BLANK, BLANK. BLANK (VERIF~~ This will be referred to as the OF profile verify screen.
Adjnsr OF Profile S«eea ADJUST TARGET - Hriaga up the verify butt. If touched. the target OF value is changed to the PROFILE value. and the display goes back to OF profiling scrxa with graph locked.
ADJUST PROFILE - Automatically shifts graph up of down to meet target UF, using the following rules, and brings up the verify button. If the verify button is touched. the display will go to OF profiling screen with graph locked.
1. All segments of the profile will be adjusted equally. with the following exception: Any segment set to minimum OF or muimum OF rata will be 'anchored.' Those segments will not be changed to meet the target OF volume.
2. If the adjustment causes any segmeat(s) to violates the minimum or maximum rates, those segments will be set to the minimum or maximum. and the remaining segments will be equally adjusted by the excess volume using Rule 1 most target UF.
3. Values will be ro,mded to one decimal places for graphical represeatatioa.
However the actual OF rate is executed and displayed is 0.01 Llhr resolution.
4. If the target OF cannot be met following these rules, as error condition will be iadicatod.
and the button will 'hook' and not change back to GRAPH UNLOCK.

' . t'(: I'/ US 93/ 10991 -i7- , The profiling graph can be altered at nay time during the treatment. Completed time segments will be reprsseated as shaded bars, which of course cannot be altered. The operator can unlock the graph as before and select an average or mantra! profile to be performed over the remainder of the treatment. The ctureat rate can be changed. and OF only can be started or sto~p~ a ~y S time during the trratmeat.
By touching the SET CALC PROFILE button while the graph is uaioclced, all ~
ptvfile segments will be net to a count rate which will :each rah ~ ~ ~~
eaed at any time the graph is ttdocked, and will fimaioa as 'clear' button during prof~g. as it its the initial profile prior to operator intervention.
If the graph has been eatertxi and verified and is altered because of a change is target OF
volume. total trot time. or an alarm causes min~um UF, touching the RESET 1~
PROFILE boson on the OF Scrnea will cause the pr~wious profile w appear on the graph.
Completed time segments will indicate the last rate performed during that segment. If the Profile does not meet Target, the operator can they totach GRAPH UNLOCK and GRAPH
VERIFY.
which wiU take the normal action described above.
Profile-Template Otxrati r~
Whey button ~ 6 on the OF profile screen is touched ('TEMPLATE PROFILES). the following buuaas appear on the right side of the screen; LAST SCg~N. MIRROR SODIUM, RECALL
PROFILE ,9~n, SAVE PROFILE Aht. BLANK. BLANK. BLANK (Verify). The functions of the Template Profile screen will be as follows;
Template Profile Screen ~ S~ - Goes bade to the OF Profile screen MIRROR SODIUM - Seta a OF profile that rrxmbles the Na profile RECALL PROFILE Aht - Renlls a profile from SRAM
SAVE PROFILE Ann - Saves the corneal profile to SRAM
W>tea the MIRROR SODIUM button is touched, the OF graph wilt 6e set to approximately the ~ XY coordinates as the Na profile. with no shifting to accommodate target OF
goal. The operator will be requirrd to verify and adjust the profile as needed.
The profile templates are intended to function as the name impiics. as templates or basic shapes only. The operator wiU be reguired to verify and adjust the prbfiie as needed.

-4g-Whoa the RECALL PROFILE button is touched, the graph will be set to the stored profile, and the VERIFY button will appear. If no profiles have been stored, the button will honk and a axxsage will appear in the instruction window indicating no profiles available.
. ' If at least one profile is available, it will be displayed in the udocked atata, and the profile number on the button will increment if another profile is available. Each subxqueat button touch will recall the react available profile and increraeat the >xta~, until tho 6th or last available -_ profile is displayed. The button will then wrap around to the first profile.
Whoa the desired prnfile is disp4yod. ~ ~ ~ ~ and LAST SCREEN to activate the profile.

The SAVE PROFILE ~n button will initially be xt to SAVE PROFILE prior to any buuon touduws. On the fast buaoa touch it wiU highlight, change to SAVE PROFILE ~fl, and the~verify button will appear. Each arbaeqtteat brttton touch will incsemeat the profile p~ition oa the button, until the 6th position is reached, which will then wrap around to the first.
Whey the Verify bwton is totached, the currant profile wilt overwrite nay previous profile stored is the memory position displayed on the button.
Button positiomff5 should be saved for 5tdue expimsion. Standard ROM'd profiles could be mcxllod with this button. as with the RECALL PROFILE d~a button feature, when and if thox are developed.
ZS Whoa the OF ONLY button is touched from the OF profile screen the graph will be eaablod for OF Ody profiled carry. The OF ONLY button will change to OF ONLY VERffY.
Whoa s xgment is touched in this mode it will highlight a 'B' is the Dialysis time bar.
indicating OF ody doting that time segment. Com~ersely, when s highlighted xgmeat is touched, it will remove the 'B' from the time bar and turn off OF ody during that seat.
If the OF ONLY VERffY button is touched, the button will change back to OF
ONLY and the selected xgmeats wiil become active.
The highlighted 'B's' wiU reasain oa the pc~ribed time axis indicating the xlectod LJF Only xgmeats. Completed. current, and future bypass time xgmeats will be displayed this way.

rt: r i t.~Sy3/ 1 U~! i -49- s Whey the machine is is OF Only the dialysata flow rate will be automatically lowered to app ~~. It will be tact to the previously xt flow rate automatically upon completion of the bypass sequence.
S . _ OF Only will override manual bypass. If manual bypass is active and the operator selects 1JF
Only for the cur:rat time xgmeat, the maattai bypass will be canalod. The manual bypass ~ ~v ~ fled during OF only, and will flash as is manual bypass. : . .
'The machine state indics<or is the lows left coma of the main scrxa will indicate OF ONLY
whey IJF Only is active. OF Only will be a sub-state of Dialyze.
Clocks and Tratmeet Parame~~
The pre~ibed trratareat time will be catered via the calculator as before.
This tune will t~1 fat time, wizich will include OF Ody time as well as dialysis time (blood and dialysate eimulstiag through the dialymr).
Separste clocks will be maintained for OF Only time and dialysis time. The dagsed trratmeat ZO time in the treattaeat time window will display elapsed total treatment time during dialyze. Botb OF Only time and dialysis time will be displayed on the IJF data report.
Dialysis time will not increase during OF Only, or during eatracorporeal or dialysste alarms.
2.5 LJF Only time will accumulate only during profiled LJF Only time periods.
It will not acxumulate during extracarporral alarms and when LJF rate is set to zero.
LTF removal will continue during aoaaual and dialysste alarm bypass.
Therefore, LTF target may be rrached prior to total trrataxat time. If so. OF rate will go to minimum anti) cad of tttat-30 meat time.
Total blood processed will accumulate ody during dialysis time. Total infused heparin will acatmulate nay time heparin is infused, including while in OF only.
35 Alarms and roessa",~es:
If the profiled OF volume does not meet the target volume, because a parameter has bees chaagod or if the user catered profile will oot adj~aet to~eet target volume w~rm.~JIZS'I' PROFILE is touched. a message will appear is the warning window prompting the operator to ~!~ ~ Profiling graph. In addition. the sudio alarm will sound iatermitteatly, approximately every 90 seconds.
If the OF rate was changod manually, the graph will be set to the new rate for tire nemaiaing treatment. If the target volume or treatment times are changed, the graph will be set to a ooostaat rate which meets target volume: Whey this oaaus, the RESTART PROFILE
buaan will sppear on the OF sc>nea and operaus as described above.
W6ea the UF. OF pro610. OF profile verify. or OF profile template acrxas are active and as e:ttraoocporeal or dialyate alarm oc~rs, the machine will go back to the main screen (PRIIbiE or DIALYZ17. If the profiling ~ is udockod, the most roast locked profile will be saved and will be displayed is the locked mode the next time the OF profiling sea is catered. If the iJF
Ody mode is scsive, the last verified tJF Oaly profiled segments will be active.
~ t~ ~ is udacked when the OF Profile Scroea is exited, beattse of all alarm or a LAST
SCREEN button touch, as error beep wiU oaxrr and a mmssge wiD appear is tha instruction window indicting 'UF profile not verified.' OF Data Report:
This data report will overlay the lastructioa Window and Alarm windows. The data included will be as follows:
ZS Times:
Trnatmeat Time . _ D~ysis Time Remaining Dialysis Time ~ E>apsed OF Only Time Remaining OF Only Time Vdtmxs:
OF Target OF Removed OF Remaining OF Oaly Target .. ~ PCT/L.~S93/10991 .-51-OF Only Removed OF Only Remaining ~SUI~SITnITE SHEET (RULE 26~

USER INTERFACE FOR UF-PROFILING
APPENDIX B
APPLICATION OF GROGAN ET AL.

s FIGS. 12-18 depict a soqueace of screen displays accompanying the following actions:
1. FIG. 12: main screen is the Prime Mode. with sll windows is the default state.
Touch the TARGET OF window.
The OF control buttons appeal.
The ma~tiatum and miaimtua Target OF values ,are displayed is the TARGET
OF window.
2. ~ FIG. 13:
Touch the TARGET OF VOLUME halloo.
3. FIG. 14: The keypad app.
Enter the volume to be t~emoved in liters.
The System 1000"' will ~Ia~e the required OF :ate.
4. FIG. 15:
To view the OF Data Report, touch the OF DATA REPORT button.
S. FIG. 16: The OF Dats Report apps.
6. F1G. 17: ..
To profile UF, touch the PROFILE OF button.
7. FIG. 18: The OF profile controls appear.
2S FIG. 19:
FIG. 19 is as illustration of the main profiling screen, or OF Profile scx~a.
Wbea the proscribed tr~eatmeat time and target OF voltume to be t~emoved are catered, the OF profile is set to a calculated value which will meet target volume over the treatment time.
1a FIG. 19, the prGSCribed trratsnetu time is S.0 boors (r~atad by a highlighted bar oa the X
axis), and the target volume is 9.50 liters. The rate has bees calculated to 9.SIJShr ~ 1.9 L/hr.
If prescribed tr,eatauat time and/or target volume are not set as error message will appear is the lower left bead corner of the graph.
The minimum and maximum OF rates art: repr~ated by a hig~ghted bar oa the Y
axis (0.50 and 3.50 Lhr. respectively). They are set is the calibration mode.
' r..........._. ,.. . . _.

-~4-FIG. 20:
t The buttons GRAPH UNLOCK/GRAPH VERIFY and OF ONLY/UF ONLY VERIFY buttons are dual function, which will be explained later. The VERIFY button (position 7) appears at appropriate times. whey a operator confir»ntioa is required.
In FIG. 20, GRAPH UNLOCK has bees touched, which removes the connecting line from the indicator "blips' and enables the graph for profiling.
The GRAPH UNLOCK button has e;haaged to GRAPH VERIFY, and the mode indicator in the lowex right hand corner of the graph indicates UNLOCK'ed status.
Notice that all blips beyond the 5 hour treatment time are set to the minimum OF rate. These cannot be altered unless the treatment time is extended.
FIG. 21:
1n FIG. 21. the operator has touched the profiling graph at approximately of 2.7 Llhr (Y axis) in the first 15 minute time xgmeelt (X axis). The blip for that time segment immediately moves to ZO the location of the touch.
In the unlocked mode the operator can "draw' s profile by touching say area on the graph. The corresponding blip for each time segment immediately troves to the location of the touch in that time xgmeat.
If the touch oaaua above the maximum OF rate (above the imaginary horizontal line st 3.5 L/hr), but within the graph era (below the imaginary horizontal line at 4.0 L/hr), the blip will be . . mowed to the maximum tste. The opposite is true for touches below the ~ainimum OF rate, and shove the graph limit of O L/hr.
The "Profiled" value at the top of the graph has bees changed to 9.54 L, reflecting the slight increase in the profile volume due to the changes in the first time segment.
This value reprrseats the integral of the profile curve, or amount of fluid that would be; removod by this profile.
FIG.22:
1a FIG. 22, the operator has touched SET AVERAGE PROFILE, which ~ the profile;
to be sex to as approximate; straight line buweea the first and last time segtneats.
This feature can be used at nay time that the profile is unlocked. sad either the first or test time segment can be adjusted.
Ia the DIALYZE mode, the fast uncompleted time xgmeat would be the starting point for the avenges profile. Completed time xgmeats are not altered at any time.
The Profiled value, has been changed to 11.50, tept~atiag the huge ~~ is the profile integral.
FIG. Z3:
3a FIG. 23, the operator has tm,~ the GRAPH VERIFY button. ~ If the Profiled value and Target value are equal, the graph will lock, the GRAPH VERIFY button will changed back to GRAPH UNLOCK, and a lice is draw through each of the blips.
FIGS. 24-Z5:
~ t~ ~e the Profile and Targex values are unequal. Therefore, whey the GRAPH
VERIFY
button is touched, the OF Profiles Adjust screen appears (~G. 24).
ZO
Dace s profile has bees selected, either manually or with the AVERAGE or CALCIJIATED
buttons, it must be verified to insure proper LTF gal.
With the scroea shown is Fig. 24, the operator has two options: Change the Target value to the:
Profiled value:. or make the profile adjust to the Target value. In this e~tample the operator 6as':
ta~chod ADJUST PROFILE, which causes the profile to shift downward to match Targex, and the Pno6led value indicates the shift.
~° ~' ~ appears once the profile has a6ifted and meets the Target. If allowed to time out (apptny S seconds) ~ profile will shift upward to its original state. Ia this e~tamples ~ VI~ffY button is t~wichOd, ~g ~ ~~y ~ ~ bacJc to the LJF Profiles scrxa with the graph locked (FIG. ZS).
The profiles is adjusted by shifting each blip up or down is equal amounts, so that the original shape of the profile is msiataine~. If for some reason the profile will not adjust, an error honk sounds sad as exrar a~ssage appesra is the Instnartion Window.
SUBSTITUTE SHEET (RULE 26~

From the scsxa of FIG. 24, the LAST SCREEN button can be touched to go back to the OF
Profile scroea with ao adjustments to the profile or Target value.
Ia FIG. 25. the shifted profile has bees verified and the OF profile scroen is present is the locked ::, If the operator Gad touched the ADJUST TARGET button on the screw of FIG.
24, the Target value would change to 11.50 and the VERIFY button would appear. Touching the VERffY
button would cause the dispisy to go to the OF Profile acs, with the Target volume set to 11.50 L, and with the graph locked in its previous condition .
If the VERIFY button times out without being touched (approxiaoately S'seoonds). the Target value will go back to 9.50 and the OF Profile Adjust screen would be active.
Ia FIG. 25. the GRAPH UNLOCK button is touched. leading to the unlocked profile shown in FIG. Zti.
FIGS. 2b-27:
1n FIG. Zb. the SET TO CALC PROFILE buaon is touched. This button functions as a "clear"
button after the original profile has been altered, tesamag the profile to the original shape (FIG. 27).
From here the opauor can draw a profile using the profile as a reference. ~ it reprr~ats the ZS target removed.
1n FIG. 27, the profile has bees "cleared" by the SET TO CALC button.
Ia some uses the calculated profile wiu differ slightly from the Target value, which wiu be indicated by a diffaeace in the Profiled and Target values. In this case, if GRAPH VERIFY and ADJUST PROFILE are touched. the profile may not shift to a pafedly straight horizontal line.
This is due to the slgorithm usod to match the profile to the Target vslue. It is "front weighted".
which taeaas that if the volume to shift is not evenly divisible by the number of remaining time sa:meats. the earliest (front) time segments will be shined by the minimum resolution until the profile meets the target.

_ . _. .....~... ...» .
FIG. 28:

~ FIG. 28, the opetstor has "drawn" a profile by touching the graph in the arraag~
by the blips. The blips pointed out by arrows have bees set to the maximum sad anioimum OF
S rates, because the touches were a or outside those limits.
Afro is FIG. 28, the operator has profilod. sad has touched GRAPH VERIFY to lode the profile.
Notices that the Profiled and Target values are not equal. Now, when the GRAPH
VERIFY
button is touched, the Adjust will appear (FIG. 29).
FIG. 29:
1a FIG. 29. the OF Profile Adjust has been displayed, sad the ADJUST PROFILE
button has been to,>ched.
IS
The xgmeats that were previously set to maximum and minimum values via at those values.
The shifting logic will not move a blip thu has bees sec to a limit, sad will not move a blip pit a limit. If, is the proxss of shifting a profile, nay blip meets or exceeds the rate limits. those blips are net to the limit, sad the excxas volume is evenly distributed (shifted) over tha rest of the profile.
FIG. 30:
1n FIG. 30, the shifted profile has been verified sad the graph is in the locked mode.
The OF ONLY button is used to program OF Only time segments. "UF Ody" is a machine state in which the OF system continues to remove fluid from the patient while the dialysata system is in bypass. during which tha dialysste is the dialyzer is stuionary.
The OF ONLY button works similar to the GRAPH UNLOCK/GRAPH VERIFY button. It enables the graph for OF Ody profiling. The OF ONLY button is disabled whey the graph is in the locked state.
To begin OF Only profiling. the GRAPH UNLOCK and OF ONLY buttons are touched in sequence.
SUBSTITUTE SHEET (RULE 26) _J8.

FIG. 31:
1a FIG. 31, the graph is in the unlocked. OF Only entry mode. The OF ONLY
button has cbaaged to OF ONLY VERIFY, which works much like the GRAPH VERIFY button is that it IocJcs the profiled values whey touched is this stata. Udike the GRAPH VERIFY
button, no .
shifting or adjustments take place with the OF Only feature.
.. -,' .. . -..
__ .~. . . . ~ ~ ~ ~y p~~Q mode, the blips will not reapoad to graph touches.
FIG. 32:
In FIG. 32, the graph has bees touched~in the third and fifteenth time segments. Any touch on the graph will toggle OF only during that segment, regardless of the OF rate limits (indicated by ~ d~ boxes). If a xgmeat is previously set to OF Ody whey touched, it will change back to non-OF Ody. ~d vico-versa. The segment status is indicated by a "B"
(Bypass) is the prescribed time bar.
Time aegmeats beyond the pnaaxibed tmtmeat time ca~ot be set to OF Ody.
Onca OF Ody segments have bees selected, the OF ONLY VERIFY button is they totach~ed, loddag the iadic:ted segments to perform OF Only. and the OF Profile xreea is displayed (FIG. 33).
FIG. 33:
1a FIG. 33, the OF Ody time segments have boea verifiod. The machine will eater the OF Only ., :fate at the :45 and 3:45 times is the treatment.
These OF Only time segments can be changed at nay time, as long as that time segment has not bees oompieted.
Also in FIG. 33. the TEMPLATE PROFILES button has bees touched. leading to tho OF Profile Templates scroea (F1G. 34).
FIG.34:
1n FIG. 34, the SAVE PROFILE button touch has causod the VERIFY button to appear and "A~l"
to be appended to the SAVE PROFILE button.

-~9-If the SAVE PROFILE al buttoa is touched again before the VERIFY button times out (approximately 5 seconds), it will change to SAVE PROFILE b2, aad the VERIFY
button timeouc will be reset to 5 socoads. Subsequent touches (prior to VERIFY button u~ut) wiU
~ ~e 'fin' to iacrtmeat up to 6. aad rhea loop bacJc to I. aad so on.
S
If the VERIFY button is touchod. the ct,>'r~t pro file will be stored in the memory 1.
iadiated oa the SAVE PROFILE Irn button, and will overwrite the profile previously stored there, If the YERIFy >m~ t.~ o~ ~ p~~e is not raved and the SAVE PROFILE inn cban~es back to SAVE PROFILE.
Also in FIG. 34, the VERIFY button is touched. and the profile is stored in location A~1.
FIG. 35:
1n FIG. 35, the Profile templates feature allows the operator to store and rt:tieve profile ~P~ ~m trmtmeat to tra~m~t. The templates are stored in static RAM where they remain eves after power loss. The SYSTEM 1000 will store and rttrieve up to 6 templates.
Also in FIG. 35, the SAVE PROFILE has bees toed, ~ ~ op~r intends to stone this profile.
F~ ~ :~ of F1G. 35, the LAST' PAGE button can be touched to redua to ~e ~
Profile scrxa.
F1G.36:
Ia FIG. 36, the operator has catered a new profile manually. This is possible any time the graph is tmlocked.
FIG.37:
In F1G. 37, the operator has tout SAVE PROFILE twice, csursing it to iadicste SAVE
PROFILE A~2. The VF,.RIFy bin is then touched, s~r~g ~e current profile in location 2.
~g~IME Sy-IEE7 (RULE 26~

~0-FIG. 38:
In FIG. 38, the operator has touched RECALL PROFILE, which csusod the buuoa to change to RECALL PROFILE 111. and caused the VERIFY button to appear. In addition. the profile stored is location A~ 1 was drawn oa the graph.
If the RECALL PROFILE button is touched again prior to the VERffY button timing out, the anal toned profile will be displayed and the number on the button will inc:aa~t (much like the SAVE PROFILE halloo). If the verify buuoo is allowed to time out. regardless of the number on the RECALL PROFILE button, the graph will go back to the original profile, prior to the first RECALL PROFILE button touch (FIG. 3~.
If the VERIFY button is touched, the cuntnt profile (indicated on the RECALL
PROFILE
button) remains oa the graph and becomes the active profile.
FIO. 39:
Ia FIG. 39, the opastor has touched the MIRROR SODIUM PROFILE button, which eases a profile to appear on the graph which resembles the Sodium profile, and causes the VERIFY
button to appear.
The Mirror Sodium feature is similar to Recall Profile, is that as unadjusted profile is made available to the operator.
To determine the mirror profile, the Sodium profile is scaled to the current OF rate limits. The sodium profile illustratod is FIG. 39 actually started st the extreme upper left hand corner of the Sodium graph. and extended to the lows right hand corner (the Sodium profile is allowed to e~toeed the treatment time limit).
The mirrored profile has bees scaled to fit within the OF rate limits which caused the upper kft corner of the mirror profile to start at OF rate 3.SOL. The lower right corner has bees truncated, due to the required minimum OF rata beyond the treatment time.
Touching the VERIFY button makes the mirror profile the active profile (like RECALL
PROFIL.ENERIFY). Allowing the VERIFY button to time out rearms the original profile to the graph.

v.~~.W .JII.
~I-' The profile interval defaults to 15 minuta segments, and can be changed to 30 or 60 minutes is ~° ~braition program. Wbea the interval is set to 30 or 60 minutrs, blips within each xg~
move coacurnatly wbea that segment is touched.
S ~~. ~:
Via. 40 shows both 30 and 60 minute intervals. The dashed box as the leR.shows the sego ., ~ ~ t~ 30 minute iataval. Any touch. within the dashed boa will cause both blips to move .>..-10 , _ .
~~. the dashed bos ~ the right shows the segment area for a 60 mute .
T6a OF Only time its are also adjustable is calibrati~.
15 . FIC3. 41:
FICi. 41 shows the same ~~ with the graph is the IJF Ody entry mode.
The 'B's' for each segment operate ~"~tly, as do the blips while profiling IJF
rat0.
ZO .
.. . ; t S~85TIZifi~ SHEET (RULE 26~

Claims (11)

CLAIMS:

1. A method of providing operational instructions to a hemodialysis system, so as to enable the system to operate according to an operational parameter that can vary over time, the method comprising:
(a) providing a user/machine interface that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system;
(b) enabling an operational parameter to be selected;
(c) enabling a time period to be entered into the system;
(d) enabling a target cumulative value corresponding to the operation parameter to be achieved while operating the system during the time period to be entered into the system;
(e) enabling a time-varying set of data corresponding to the operational parameter to be executed by the system during the time period to be selected, the set of data being representable as a plot of coordinates in a region defined by an ordinate of values of the parameter and a time-based abscissa, the plot defining a proposed cumulative value of the parameter; and (f) adjusting the time-varying data to make the proposed cumulative value equal to the target cumulative value, so as to allow the hemodialysis system to achieve, while operating, the entered target cumulative value within the time period.

2. A method according to claim 1 wherein the operational parameter is the ultrafiltration rate.

3. A method according to claim 1 wherein the operational parameter is the sodium concentration of the dialysate.

4. A method of providing operational instructions to a hemodialysis system having ultrafiltration capability, so as to enable the system to perform ultrafiltration of fluid from a patient according to a time-variable set of ultrafiltration data, the method comprising:
(a) providing a user/machine interface that displays information relating to a hemodialysis treatment and allows a user to control functions of the hemodialysis system;
(b) enabling an indicium corresponding to ultrafiltration to be selected;
(c) enabling a prescribed time for dialysis to be entered into the system;
(d) enabling a target ultrafiltration volume of fluid to be removed from the patient to be entered into the system;
(e) enabling a proposed time-variable set of ultrafiltration data being representable as a plot of coordinates on an ultrafiltration rate axis and a time axis and defining a proposed ultrafiltration volume to be selected; and (f) adjusting the proposed time-variable set of ultrafiltration data to make the proposed ultrafiltration volume equal to the target ultrafiltration volume, so as to allow the hemodialysis system to achieve, while ultrafiltering the fluid according to the adjusted ultrafiltration data, the entered target ultrafiltration volume within the entered prescribed time.

5. A system for performing hemodialysis comprising:
(a) a dialysate-delivery system for supplying dialysate to a hemodialyzer;
(b) a blood circulation system for delivering blood from a patient through a blood compartment of a hemodialyzer, and back to the patient;
(c) a user/machine interface operably connected to the dialysate delivery system, the user/machine interface displaying information relating to a hemodialysis treatment and allowing a user to control functions of the hemodialysis system, said user/machine interface being operable to allow a user to select a prescribed time for dialysis, a target ultrafiltration volume, and a proposed time-variable set of ultrafiltration data; and (d) a processor which adjusts the ultrafiltration data selected by the user to allow the hemodialysis system to achieve, while ultrafiltering the fluid according to the selected ultrafiltration data, the entered target ultrafiltration volume within the entered prescribed time.

6. The method of claim 1, wherein the user/machine interface includes a touch screen and at least one of steps (b) to (e) is enabled via the touch screen.

7. The method of claim 1, wherein enabling the time-varying set of data to be selected includes recalling the set of data from a memory.

8. The method of claim 4, wherein the user/machine interface includes a touch screen and at least one of steps (b) to (e) is enabled via the touch screen.

9. The method of claim 4, wherein enabling the proposed set of ultrafiltration data to be selected includes recalling the set of data from a memory.

10. The system of claim 5, wherein the user/machine interface includes a touch screen.

11. The system of claim 5, wherein the user/machine interface is operable to allow the user to select the proposed set of ultrafiltration data from memory.